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This piece really does not hit on the reason Diesel is not popular in the US. Back in the 1970s energy crisis, diesel cars drew some interest, and unfortunately General Motors obliged with some horrendous products. Smelly, smokey, slow, and highly trouble prone diesel engine that was essentially a gasoline 350 cubic inch V8 block with diesel heads slapped onto it. Used in Oldsmobiles, Chevys, and Cadillacs, it was a disaster and ruined the diesel concept for decades.

See http://www.autosavant.com/2009/08/11/the-cars-that-killed-gm... for some history.

"What's good for GM is good for America" used to be a quote around Washington. What an awful company, and a cautionary tale about taking "public/private partnership" way too far. GM also ruined Los Angeles -- look up the transit system LA/OC used to have prior to GM's purchase of it and lobbying. LA would be a much nicer and more livable city had GM not had such influence.

GM really should have been allowed to die in 2008.

AFAIK, the reason why it wasn't was that it would ruin the supply chains of the other automakers.
Not sure why you're being downvoted. That's a huge part of the reason: Due to the nature of the auto industry, many suppliers only have a few customers; take away a third of a company's business, and there's a good chance it will fail.

The entire economy of Michigan (and many neighboring states) would have collapsed. Over here in West Michigan, we have many companies—ranging from mom-and-pop injection mold shops with 50 employees to large companies like Gentex, Delphi, etc. Those companies were already struggling back in 2008; GM going away would have meant the death of most of them.

I hate many of GM's historical business practices as much as anyone (there used to be two streetcar lines within a quarter-mile of my home, dammit), but the saving of GM was a critical component in preventing a catastrophic depression, especially for Michigan—which was already suffering before the Great Recession hit.

IIRC, even companies like Toyota who were not in trouble wanted to keep the supply chain around and thus favored the bailout.
It's not all or nothing, the government could have broken GM up into component parts as a condition of a bail out. AKA killed GM but kept the parts. Chances are many parts would have failed and been bought up over time but as smaller companies the market could have dealt with this much easier. There many have also been some part that becomes much stronger when no longer part of the collective.

EX: Verizon vs. the old AT&T and the new AT&T.

BIG DISCLAIMER: I WORK FOR GM! Disclaimer: What follow are my personal opinions!

Given the above, I do not think GM has always been right. GM has been part of many morally questionable practices. I think GM was on a terrible course from the mid 1970's to the early 2000's[0]. Those diesel engines in particular were incredibly shitty. My dad was one of those guys who loved the idea of diesel and who got the stares and the smirks.[1]

In the early 2000's they started to try to change. It is very difficult to change a large organization like GM.[2] I don't think today's GM is the same GM from 1920, 1939, 1970, or 1990. If it was, I wouldn't work here.

Many say it would have been worth it to let GM die. Under circumstances other than the 2008 economic downturn, it might have been.

Much of the severity of the 2008 crisis was largely (immediately) due to shock related to the collapse of Lehman Brothers [3] and the refusal of anyone to take over those assets at any price.

Very few people worked for Lehman Bros. A LOT of people work in the automotive ecosystem.

Before bailing out GM, the govt and GM DID look around for other financing/buyout options. No one wanted to take that on.

The saying "whats good for GM is good for the country" is largely outdated nowadays, but many people still think that way, and the collapse of GM would have been psychologically devastating, as well as financially devastating to many thousands of people.

[0] The infamous "ignition switch" design process started in 1997 (Valukas PDF page 35). The Valukas report is very interesting, I recommend it for everyone who is interested in system design. http://www.nhtsa.gov/About+NHTSA/NHTSA+Electronic+Reading+Ro... (bullet 4)

[1] My family has owned a 80's VW diesel rabbit, an 81 diesel Audi 5000 (20 years old at time of purchase), an 80's diesel Suburban (terrible engine), and various diesel work trucks.

[2] GM is not a single organization. It is more accurate to think of all the external organizations such as: UAW-GM, GM branded dealerships (which are not owned by GM), GM Suppliers (which also supply other companies). Then there are all the internal organizations: GM Truck Manufacturing, GM Car Manufacturing, Global Brands, etc, etc, etc.

[3] http://en.wikipedia.org/wiki/Causes_of_the_Great_Recession http://fcic-static.law.stanford.edu/cdn_media/fcic-reports/f...

From the above: In addition, the government’s inconsistent handling of major financial institutions during the crisis—the decision to rescue Bear Stearns and then to place Fannie Mae and Freddie Mac into conservatorship, followed by its decision not to save Lehman Brothers and then to save AIG—increased uncertainty and panic in the market.

>GM has been part of many morally questionable practices. I think GM was on a terrible course from the mid 1970's to the early 2000's

Yeah, erm.. about that timeline.

http://www.usatoday.com/story/money/cars/2014/02/18/gm-cobal...

I think it's safe to say GM didn't exactly clean up its act after the early 2000's. If I did that same thing with my small business, I'd probably be charged with manslaughter by gross negligence... or perhaps outright murder since I knowingly allowed innocent people to die in order to rake in more cash.

> If it was, I wouldn't work here.

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Every death and injury caused by those ignition switch failures was a tragedy. The attitude of the managers involved was wrong. The technical understanding of the complete system was unacceptable. It should not have taken as long as it did, and the defects should not have left the planning process, much less the plant.

That being said, I do still think that the course was changing. The ignition switch in question was designed in 1997. Vehicles are hideously complicated; Conway's Law[1] would indicate that the organizations involved would also be hideously complicated, and they are! The Valukas report mentioned above calls out specific shortcomings in this regard.

If your small business produced vehicles on the scale of GM, I would be very very surprised!

[1] http://en.wikipedia.org/wiki/Conway%27s_law

>The attitude of the managers involved was wrong.

That's a very corporate shill way of putting it. Their actions were murderous. They let people DIE.

Do you not GET THIS somehow or are you attempting to gloss over this issue?

>If your small business produced vehicles on the scale of GM, I would be very very surprised!

Please don't be disingenuous with artful dodging. You're not smart enough to get away with that with me, sorry. I'm VERY OBVIOUSLY not discussing an issue of complexity, I was discussing an issue of ethics and morality.

It's an issue where GM knew they were killing people and did nothing about it for a long time because it wasn't profitable.

No wonder the GM corporate culture is so twisted. You're trying to turn this around as an attack on my supposedly "simple" business instead of owning up to the fact you work for a scummy corporation that killed people in the name of the almighty buck.

You may not want to face that fact and instead go running to another wikipedia link on humorous adages in hopes of distraction, but I'm not falling for it, guy.

People are dead because of your company's lack of ethics. GET IT?

If your goal here is to be public relations for GM, you're failing miserably and I suggest you move along. You're just making me resent GM even more. If you were my PR person, I'd fire you for incompetence.

But, that's how I run MY business anyway.

Speaking of GM and diesel, their upcoming Colorado diesels are very appealing. After trips abroad, I come back lusting after those types of small/midsized workhorse trucks.
Whatever you think of GM today, I find this half-hour movie from Chevrolet-making in 1936 absolutely fascinating:

https://www.youtube.com/watch?v=8bT6txm4RpA

This was slightly before the great strikes in Flint, Michigan, and those working conditions are obviously both hazardous and extremely inconvenient. But it shows what an amazing enterprise a large car factory was already then, and the world has come far since those days.

Charles Wilson, who was in Eisenhower's cabinet, said that he had assumed that what was good for America was good for GM and vice-versa. In the context it was less obnoxious than it now sounds--he meant that a strong economy benefited both.
Charles Wilson, who was in Eisenhower's cabinet, said that he had assumed that what was good for America was good for GM and vice-versa. In the context it was less obnoxious than it now sounds--he meant that a strong economy benefited both.
Not having grown up in the U.S. I can say that diesel left this same impression for a very long time in the international markets. Only in the past 15 years or so has diesel been tamed for the consumer to not be as noisy and smelly.
That started much earlier in continental Europe, during the 80s for the biggest sedans and 90s for smaller cars, with the concurrent mainstreaming of catalytic converters (smell and soot), turbos and better diesel (lower knocking and thus less noise).

15 years ago was the mainstreaming of common rail direct injection and particulate filters (on passenger cars) which cemented that

They why aren't they trying to market diesels to those of us who were born less than half a century ago..?
I think history and culture play a big role in this.

Eg: in my country automatic cars are not popular and it not about the price, even in top segments cars people think that automatic cars are bad

Americans really want to drive diesels. There is a huge demand for diesel volkswagens.

The supply just isn't there; maybe there is a lag between cost-unconscious new-car buyers [ordering new cars], and cost-conscious used-car buyers [buying what the new car buyers leave].

Source: I used to work in the automotive remarketing industry.

They can be good cars. For years I drove a 25 year old Mercedes 300D. It was cheap to buy, nice to drive and extremely reliable. Unfortunately rust finally got it.
Might be a great car to drive but I've lost count of the times I've cursed a 300D in front of me for fouling the air I'm breathing. They're just awful to follow in traffic.
Modern diesels are quite different, though. They've got particle matter filters so not much smoke coming out.
May be, but as far as I'm concerned those 300Ds can't rust away fast enough.
They are certainly not as clean as a modern diesel but if they are properly adjusted they aren't bad. Most of the smokey ones probabley haven't been maintained for years.
In Germany we have mandatory 2-year checkups by a licensed inspector (TÜV/DEKRA) for normal cars and 1-year checkups for trucks, buses and taxis.

This includes not only a visual inspection of all safety-relevant parts of a car but also a check of the emission values.

How is this handled in the US?

About the same in California; mandatory emissions check every 2-years. In the case of a private sale, if the owner has not had it inspected within 90-days of sale the buyer is required to have it inspected upon registration.

There are exceptions with older (vintage) cars, and relatively new cars.

As with most things, these laws vary from state-to-state, and even county-to-county within said states.

California is known for having the toughest regulations in this area.

Kentucky had a limited emissions inspection regime from 1999-2005, when it was killed by the Republican governor. The only current inspection requirement I know of is if you purchase an out-of-state used vehicle. We have plenty of ancient cars on the road that have never been inspected.

Sometimes police officers will pull you over if you have obviously-broken headlights or such, and tell you to fix it, but not often.

Wikipedia has a decent article about where in the US emissions testing is required:

en.wikipedia.org/wiki/Vehicle_inspection_in_the_United_States

It's on a per state basis, and sometimes per county. There's no inspection in Ohio, but an annual one is required in Pennsylvania. Also in certain counties of Pennsylvania, an emissions test is required for anything that's not a heavy duty truck. I wish they would require them for everything because I have to hold my breath every time a dump truck comes by.

Source: I have an appointment for car inspection this morning.

Edit: certain counties

In some states emission testing is only required in certain areas of the state. For example, in Georgia only cars registered in Atlanta-area counties have to be emission-tested. (Also, cars less than three years old are exempted.)
Loved our Volkswagen Sportwagen TDI.

One of the problems is that VW that they add premium options to the TDI marque. So you can't get a bare bones Jetta TDI without the highest trim level, fancy wheels, and other things that add to the cost. On top of that the gasoline ones are efficient enough where the price difference becomes a non-factor, even when taking the MPG into account.

They are damn fun to drive though, torquey without the compromises of a 4 cylinder gasoline engine. The used market on the sportwagens is great too, which is why we ultimately traded it in for a Tiguan since the demand for the wagens was high enough to make that a relatively easy financial decision.

Unfortunately VW doesn't do diesel Tiguans in the US, which is weird, you'd think the SUV market would be a no-brainer for TDI.

I seriously considered the Golf TDI, and didn't mind the premium options, but I ended up not liking the high-torque of the turbo diesel on the front (both my wife and I could picture us slamming into the back of someone in DC traffic), and went with the GTI instead.
I owned a 2009 Golf TDI and loved every minute of it. The car was simply a blast to drive. In the 18 months I drove the Golf I didn't have any issues with high-torque. In fact, the turbo lag guaranteed you wouldn't slam into the car in front of you unless your foot was firmly planted for multiple seconds.

The fantastic fuel economy was the icing on the cake.

Are you serious? Isn't the GTI still faster?
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The GTI is faster but has less up-front torque. The issue was not hurtling down the highway at high speed (both can do that perfectly ably), but the feeling we both got that the combination of early torque and turbo lag just begging for the car to surge forward unexpectedly and rear end someone.

The GTI gets rid of one of those problems, and is a spectacular car in its own right.

Simple solution: shift earlier, since you can shift up at 2k (before the turbo really takes off) without lugging the engine at all.

Complex solution: Chip the engine - some people prefer a smoother power curve, which can be achieved with a tune.

I don't feel like driving a manual in a busy city, and much prefer letting the more fuel efficient dual clutch transmission do the work.
Understandable (except for the "more fuel efficient" bit), but with your reply to @huuu in mind, being able to select your gear (and keep it in that gear) would eliminate any unexpected surging. Dense traffic isn't a lot of work in a TDI, because you don't need to shift frequently if at all. In my experience 2nd gear covers between 10-35mph comfortably. I have a 1.25 hour commute that's a mix of stop-and-go in small towns and highway, and the TDI is great for every bit of it.
Everything I've seen suggests the dual-clutch automatic transmission is more efficient than the manual, including VW's own figures. It came as a surprise to me, but a nice benefit for other factors.

I imagine that yes, being able to keep it in low gears would have helped, and indeed putting it into manual mode for some of the parts I found the worst (rapid turns from one busy street to another) helped, but it put it in the "More trouble than it was worth" category.

That being said, the TDI was a great car, and a serious contender for my money. I just preferred the GTI a bit more, but given I love the GTI, that's good company to be in.

The published numbers say that. The real world numbers say very much otherwise. The manual CRUSHES the DSG, often by 4-5mpg or even more for some drivers, especially on the highway.

It's geared lower, for one thing, only 2000rpm at 75mph.

FWIW, I traded in a 2012 TDI with the DSG for a manual Mk7 a few days ago. Love the stick, although it's taking some getting used to (this is my first manual).

Also in the manual's favor is the $1,100 cheaper upfront cost and not needing a ~$400 transmission service every 40k.

Interesting. I'm rather fond of my DSG, and manual was a little bit of a non-starter because my wife wanted a car she could drive, and learning stick in DC is...a terrible idea.
Couldn't agree more about how much fun the TDI's are to drive! Simply a blast on tight, curvy roads.

Your note about the Tiguan makes me sad. I'm moving back to the US next week and was seriously thinking about getting a Tiguan (and hoping for a diesel). I'll add the Sportwagen TDI to my list.

Rumor is that the MQB platform Tiguan will be available in TDI, but I think that's not expected until MY2017.

Wagen is a great vehicle. I love mine.

Can someone copy and paste the article. Its behind a location based IP wall:

"BBC Worldwide (International Site) We're sorry but this site is not accessible from the UK as it is part of our international service and is not funded by the licence fee. It is run commercially by BBC Worldwide, a wholly-owned subsidiary of the BBC, the profits made from it go back to BBC programme-makers to help fund great new BBC programmes. You can find out more about BBC Worldwide and its digital activities at www.bbcworldwide.com."

Such a stupid policy to be honest. I live in the Uk and pay my licence fees too.....

A week behind the wheel of the wholly agreeable Audi A6 TDI (pictured here) prompts us to revisit this story, which first appeared on BBC Autos in 2013.

In Europe, if a motorist wants to drive a small car that feels like a big one, there is a diesel for every occasion. A 1.6-litre turbodiesel delivers the torque surge of a much larger gasoline engine, yet with the fuel efficiency of a much smaller one. In the UK, diesel sales account for more than half of all cars sold, and even with a stat like that, Britain lags the rest of Europe, which has long preferred diesel to gas.

So why would more Americans not drive diesels? From the European perspective, it would suit the driving style of the States perfectly, with lots of relaxed muscle available at low rpms to cruise vast interstate networks that are the envy of the world. Better mileage means fewer fill-ups, and the on-paper improvements in fuel economy would, overnight, take the US fleet one massive step toward President Obama’s targeted 54.5 mpg national average by 2025. Simply stated, diesel should “work” in the US. “But what do Britons know about our market?” an American might opine. Quite a lot. In significant ways, the diesel market in the US is similar to that of the UK three decades ago.

In the UK of the 1980s, diesel drivers were outcasts. They were required to fill up around the back of the station, over by the truckers, to be looked upon by gasoline burners with a mixture of pity and smugness. And that presumed diesel drivers could even find somewhere to fill up, as not every filling station bothered to stock their fuel.

This sheer lack of availability led to great variability in pricing. As the only filling-station proprietor in 25 miles to stock diesel, Mr. Smith could subsequently charge more or less whatever he wanted. A survey of diesel prices in the US illustrates a similarly maddening snapshot of how scarcity can produce wide price fluctuations, with pump prices varying by up to 50 cents a gallon. But with more diesel purchasers, the laws of the marketplace would kick in, bringing prices into greater alignment. Given the need for low-sulphur refining, diesel would not necessarily become cheaper than premium in the US. It is pricier on the other side of the Pond, too, but although Europeans gripe about it, they still know the savings add up. Diesel generally returns 30% better mileage than gas, and in the dominion of $8 gallons, this is no small advantage.

Mind you, there are two distinct factors working in favour of Europeans’ wallets: fuel with a higher cetane rating, which makes it easier to control NOx emissions, and EU emissions standards that are generally comparable to the US’s Tier 2 standards in all areas apart from, yes, NOx. Even our EU 6 standards, due in 2015, do not quite match the States’ strict limits on smog- and acid rain-causing emissions.

Relative to a gasoline-burning engine, it is more difficult to control NOx in a diesel, which is why, to meet those comparatively stricter emissions limits, diesels in the US are required to use expensive, onboard after-treatment systems, which decrease the amount of particulate matter that leaves the tailpipe. Diesel engines are already more expensive to develop than gasoline units, given their turbos and complex injection systems. After-treatment systems make them even pricier. Here’s the thing: It’s worth it. Diesel used to be a dirty fuel and a dirty word, but recent technologies have addressed both problems, which is why the world outside the United States thinks of the choice between gasoline and diesel as a foregone conclusion. And even with the additional costs, passed on to the consumer, of emissions compliance equipment, the sensory pleasures of a diesel-powered vehicle are difficult to deny.

It is high time, America, to give diesels a better look.

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It's highly irritating. I proxied in and got this:

In Europe, if a motorist wants to drive a small car that feels like a big one, there is a diesel for every occasion.

A 1.6-litre turbodiesel delivers the torque surge of a much larger gasoline engine, yet with the fuel efficiency of a much smaller one. In the UK, diesel sales account for more than half of all cars sold, and even with a stat like that, Britain lags the rest of Europe, which has long preferred diesel to gas.

So why would more Americans not drive diesels? From the European perspective, it would suit the driving style of the States perfectly, with lots of relaxed muscle available at low rpms to cruise vast interstate networks that are the envy of the world. Better mileage means fewer fill-ups, and the on-paper improvements in fuel economy would, overnight, take the US fleet one massive step toward President Obama’s targeted 54.5 mpg national average by 2025. Simply stated, diesel should “work” in the US.

“But what do Britons know about our market?” an American might opine. Quite a lot. In significant ways, the diesel market in the US is similar to that of the UK three decades ago.

In the UK of the 1980s, diesel drivers were outcasts. They were required to fill up around the back of the station, over by the truckers, to be looked upon by gasoline burners with a mixture of pity and smugness. And that presumed diesel drivers could even find somewhere to fill up, as not every filling station bothered to stock their fuel.

This sheer lack of availability led to great variability in pricing. As the only filling-station proprietor in 25 miles to stock diesel, Mr. Smith could subsequently charge more or less whatever he wanted. A survey of diesel prices in the US illustrates a similarly maddening snapshot of how scarcity can produce wide price fluctuations, with pump prices varying by up to 50 cents a gallon. But with more diesel purchasers, the laws of the marketplace would kick in, bringing prices into greater alignment.

Given the need for low-sulphur refining, diesel would not necessarily become cheaper than premium in the US. It is pricier on the other side of the Pond, too, but although Europeans gripe about it, they still know the savings add up. Diesel generally returns 30% better mileage than gas, and in the dominion of $8 gallons, this is no small advantage.

Mind you, there are two distinct factors working in favour of Europeans’ wallets: fuel with a higher cetane rating, which makes it easier to control NOx emissions, and EU emissions standards that are generally comparable to the US’s Tier 2 standards in all areas apart from, yes, NOx. Even our EU 6 standards, due in 2015, do not quite match the States’ strict limits on smog- and acid rain-causing emissions.

Relative to a gasoline-burning engine, it is more difficult to control NOx in a diesel, which is why, to meet those comparatively stricter emissions limits, diesels in the US are required to use expensive, onboard after-treatment systems, which decrease the amount of particulate matter that leaves the tailpipe. Diesel engines are already more expensive to develop than gasoline units, given their turbos and complex injection systems. After-treatment systems make them even pricier.

Here’s the thing: It’s worth it. Diesel used to be a dirty fuel and a dirty word, but recent technologies have addressed both problems, which is why the world outside the United States thinks of the choice between gasoline and diesel as a foregone conclusion. And even with the additional costs, passed on to the consumer, of emissions compliance equipment, the sensory pleasures of a diesel-powered vehicle are difficult to deny.

It is high time, America, to give diesels a better look.

It does seem strange, doesn't it?

I've heard that it's because the BBC is forbidden from showing adverts to UK citizens, and since they have a little "promoted content" box at the bottom of the page they have to block it from you.

Something along the lines of if they show you adverts, they lose that TV license funding, which would be catastrophic.

I have no idea if that's true, but it passes the sniff test.

I'd love to know the reason. Slightly off topic though admittedly.
Within the UK the BBC is not allowed to run advertisements, or promote or endorse products. It's part of their charter. The funding for the BBC comes via the TV License and the revenue generated by BBC Worldwide (the commercial arm).

For viewers outside the UK there is no such restrictions and given that funding for digital ventures by the BBC is now somewhat limited (due to complaints by the commercial sector that they could not compete with the BBC) they try to recoup some money by running advertising.

It's funny they use location to block the site rather than block the ad. They could use the space for links to other articles.
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BBC Worldwide is a propaganda service, much like RT, PRESS TV, Deutsche Welle, or Voice of America.

None of these are created for a home audience, they are to advance the interests of their host nations globally.

BBC Worldwide is a commercial enterprise, set up to make money from BBC productions; the UK government may like the perception of the UK it creates abroad, but that's not its explicit purpose. The explicit propaganda arm of the BBC, the equivalent of Voice of America, is the BBC World Service, which until last year was directly funded by the UK Foreign Office.
Because in the mid 1970s Oldsmobile decided to produce a 350cu in(5.7litre) diesel based on the gasoline version of the engine. It failed spectacularly since it was not rugged enough to withstand the pressures of compression combustion. Plus GM had a crisis of quality at the time so it just sucked. While you could get German diesels all the while it was too expensive to be mainstream and most people's experience with diesel is that of heavy duty trucks. These are noisy, produce huge amounts of soot and are sometimes(note the word sometimes) driven by folks who must compensate for their manhood with such niceties as Calvin pissing on a different brands logo, taking the engine branding and making it a sexual double entendre, putting a giant 8" exhaust pipe in the bed(or more than one) or the ever popular set of testicles hanging from the bumper. So diesel suffers from an image problem here in the US.
The smoke-belching pickups have been modified. They don't come that way from the factory; diesel today is very clean.

There is a certain subculture of diesel pickup truck owners who alter the engine management computer with aftermarket chips to make it inject a ton of extra fuel, which doesn't burn properly and creates the black clouds of smoke.

I totally agree. However particularly in the southern US where I live, these modified ridiculous diesels are a pretty vocal minority. To the point where anecdotally, at least, people associate diesel to that. I'm a huge diesel proponent, my next car will likely be an "oil burner"
Correct me if I'm wrong, but I don't think it would be feasible to move all or most cars in the US to use diesel. Diesel, gasoline, and jet fuel are all petroleum distillates that boil off at different temperatures. So each barrel of oil contains so many units of gasoline, so many units of diesel, and so many units of jet fuel/kerosene/mineral oil/whatever.

And I believe that you get much more gasoline out of a barrel of oil than you get diesel, so moving many cars over to diesel would actually increase oil consumption it seems.

Diesel isn't a fuel type, it's an engine type. What we call "diesel fuel" is really just fuel better suited for burning in a diesel engine than gasoline. We also have techniques for refining some hydrocarbon chains into different ones, which means we can focus production on one fuel type.
The engines are designed quite specifically for the type of fuel that will be burned in them. Although technically you could make a diesel engine that would burn normal petrol, it would not be advisable to put normal petrol in a diesel car, because the engine relies on the fact that diesel is a better lubricant than petrol. Also, various components (such as fuel filters, fuel pumps, etc) also depend on the fuel being of a certain type, and would be damaged or otherwise fail to work with the wrong fuel.
The bigger problem (other than lubrication) is managing the moment of detonation. Petrol would explode way too early in the cycle of injection, that's why it will damage a diesel engine.

s/compression/injection/

In a diesel engine, only fresh air is in the cylinder during the compression cycle. At the top of the compression cycle, that's when the fuel starts to be injected and immediately burns/explodes. There's other reasons why petrol in a modern diesel engine wouldn't work, but i don't think pre-ignition/detonation is one of them.

"Throttle" in a diesel actually controls for how long the injection takes place.

Yes, that's all correct.

But the fuel injected does not detonate immediately, it is allowed to spread out a bit and the chambers are shaped to channel the detonation. It's a short interval but it is an interval. Injecting gasoline at those pressures and temperatures would mean instantaneous detonation of the fuel injected, too early in the cycle which will cause damage (to the injector, and to the crankshaft and/or pushrod bearings because they'll have to deal with more force than what they were designed to cope with because the energy is liberated in a much shorter time-frame). At best this will cause severe degradation of engine life, at worst immediate failure.

Another issue is that the injectors are carefully shaped to deliver a mist of fuel and the properties of gasoline and diesel are sufficiently different that the droplets will be of the wrong size and won't separate cleanly from the injector before detonation occurs.

All in all, not something you want to experiment with so if you find that you've 'gassed up' your diesel vehicle better drain the tank instead of taking your chances.

In winter in Canada it is common to put about 5% gasoline in the diesel fuel to overcome temperature effects on the diesel fuel.

Diesel is a different mix of longer carbon chains than gasoline and I'd think that makes it a different fuel type.
Nope...pretty sure its not a question of diesel OR petrol. I don't know the chemical details, but thats what I deduce by the pricing and availability of diesel everywhere else.
Used to be this way. Diesel used to be something of a waste product from refinining gasoline. As a result it was both somewhat dirty and also cheaper than gasoline.

Today, refining technology and hydrocracking allows a barrel of oil to be refined almost completely into whatever end product the refiner wants. Diesel, kerosene, jet fuel (which are all pretty much the same thing actually) or gasoline. So now these refined products are priced more by their energy content which is why the pricing has flipped and diesel now costs more per gallon than gasoline (but can still be more economical overall).

> Diesel used to be something of a waste product from refinining gasoline

It depends, but anyway it's more certain that originally gasoline was a waste product from refining lamp oil (which is closer to diesel).

There didn't use to be any "diesel fuel", Diesel designed his engine to work on plant oils and other renewable (for some value of renewable that's better than gasoline, but more at odds with food production). The oil industry realized that they could also produce something that could fuel diesel engines, and they called it diesel fuel.

Modern diesel engines are very different -- but for eg. industrial and military use, you'll still see some resilient engines that can burn pretty much anything you throw at them, from butter to diesel fuel.

Shame he fell of a boat in the English channel and drowned.

You can fuel a Humvee with JP-8, which is jet engine fuel. It's been a long time, but I remember there being problems if you switched fuels -- if you had been using regular truck diesel and switched to JP-8 you could have engine problems because you'd still have some residual truck diesel mixing with the JP-8.
It might demand greater production, but the higher efficiencies of diesel engines would mean less of what was refined would be needed for transportation (admittedly not perfect). And we would have to find something to do with all that surplus gasoline... which makes biofuels look more appealing (I run B50 or B99 in my VW, depending on the season), or better yet, using solar power to synthesize diesel fuel.
Oil refineries are nowadays complex factories that convert crude oil into lots of different distilled products. When you process a barrel of crude oil, you're not restricted to some proportion of gasoline, some proportion of kerosene and diesel and whatever. You can basically turn it up to produce more gasoline, or more diesel fuel, or whatever. The losses aren't significantly different.

You can get more gasoline out of a barrel of oil, but you can also get more mileage out of a litre of diesel than litre of gasoline. Diesel has higher energy content.

What's more, diesel fuel can be made from biological materials as well. In fact, we have had people drive their diesel cars with discarded frying oil used in hamburger restaurants to make fries. You have to filter it, and you won't make the current EU emission standards, but for moving a vehicle, it works all right.

Whether it is feasible to move all or most cars in the US to use diesel is then another matter. Diesel engines are a bit noisier, for instance, so someone might object that.

But the everyday driveability of a car with diesel engine, particularly a modern one with turbo, is nice. Lots of torque on low rpm's so it's easy to drive.

I would love to drive a diesel, but the choice is limited to mostly VW. There are no minivans in US market that run on Diesel and SUVs that run on diesel are marked about 4k+ compared to their gasoline cousins. The other thing is cost, Diesel costs more and if you factor the mileage/cost in most cases gasoline comes ahead. The beauty of Diesel engines is ability to run on Biodiesel, which is better than ethanol/gasoline flex-fuel engines which for whatever reason are popular (in terms of availability). All in all Europeans have tremendous choice with their Diesel vehicles, Americans do not. It is egg and chicken problem. I think on top of it there is some Diesel pollution related regulation, which is stringent in US than in Europe, preventing car manufacturers simply moving around European Diesel models to US.

edit: mostly german manufacturers VW, MB are trying to bring diesel, where as Japanese and American manufacturers are barely testing waters, actually FIAT-Chrysler is the one testing waters.

Car makers like Toyota, Mazda and the like all make diesel versions of the same cars-- they sell them in the UK and Australia. They cannot import them to the USA because of the "anti-smog" rules. IT's not chicken and egg-- the cars are there, and produced for other markets.

It's pure regulation.

What is it that prevents Toyota and Mazda from selling those diesel cars when most manufacturers are already selling pickups with large diesels?
Not sure, but there could be regulatory reasons. In the US there are these funny quotas for having to have so and so many cars below certain fuel consumption levels. And those quotas do not apply to pickup trucks, because they are not cars.

This is rather silly, but it's the kind of thing that comes up when environmentalists and industry lobbyists are unleashed among politicians.

> This is rather silly, but it's the kind of thing that comes up when environmentalists and industry lobbyists are unleashed among politicians.

Industry lobbyists - accepted. But why should environmentalists accept such stupid, environmentally harmful laws?

It's not easy to see how the mechanisms actually work, but I suppose it happens because those negotiations are more about power games than actual, rational processes towards specific goals.

The relevant emission regulations are described in http://en.wikipedia.org/wiki/Corporate_Average_Fuel_Economy

"CAFE has separate standards for "passenger cars" and "light trucks", despite the majority of "light trucks" actually being used as passenger cars. The market share of "light trucks" grew steadily from 9.7% in 1979 to 47% in 2001 and remained in 50% numbers up to 2011."

Thus, the very legislation designed to reduce emissions has resulted in Americans buying bigger and bigger vehicles. From Europe, the rationale for this legislation is hard to understand.

The article touches on this a bit. The US has stricter anti-smog restrictions on particulate and NOx emissions. The gap is in regulation is narrowing though, so some time in the near future (next 10-15 years) we should have parity in regulation, which will mean parity in market offerings. Until then, the initial purchase cost of a diesel powered car in the US will run higher than the gasoline powered equivalent. When you do the math, your driving needs and ownership schedule (how long you'll keep the car) must meet a specific set of parameters for the more expensive diesel to catch up on ROI.
Chrysler is starting to bring in some passenger diesels particularly the Jeep Grand Cherokee and the Dodge Ram 1500 ecodiesel.

Diesels are more expensive though, perhaps inherently so. The cost of the high-pressure injector system and turbocharger required raise the engine and maintenance costs considerably.

Modern pollution controls (a good thing) have reduced the MPG advantage enough that the fuel cost differential with gasoline is no longer an advantage. It may be that will improve as the industry gains a decade more experience in diesel pollution controls.

Dodge sells diesel Sprinter vans in the US
I purchased a new car in 2014. Having a familiarity with Diesel engines, I wanted to buy a Diesel. Even better- one of the cars I was keen about was available in Diesel form.... but in the UK only. The american version seemed to get about half the gas milage!

The reason we can't get Diesels is the environmentalist "anti-smog" campaigns of the 70s and 80s, produced emissions standards that prevent Mazda from just importing that car they sell freely in the UK.

Mazda is has been trying to get their Mazda3 Diesel version imported to the USA for a couple years. It's becoming a bit of a joke because they keep thinking they are going to be able to do it and then not being able to get the permits.

Environmentalists really hated diesels in the 70s and the 80s because "smog" and the particulate matter that diesels produce was the big scary thing.

Now gas milage is the big desire but the emissions standards make that nearly impossible.

When I was a kid I had a Toyota Tercel station wagon. That car got 40MPG Highway! And it wasn't an econobox- it was 4WD and a big old station wagon (well big for japanese standards.) Meanwhile, I just bought a 2014 RAV4--- 30 years newer with 30 years more advanced technology-- it's about the same size and weight, also with a 4 cylinder engine but much more efficient computer controlled shifting and the like-- yet it only gets 20mpg highway.

MPG and emissions are a tradeoff-- and the regulatory demands of environmentalists don't seem to take this into account.

To be fair to the car makers, diesel fuel in the US is allowed to have a much greater level of sulfur than in other countries, so the typical level of emissions for the same vehicle in the US is worse than in other countries.

If the EPA were to mandate lower sulfur levels (not likely in this century) then our diesel cars would be better.

Or simply create another grade of Diesel- similar to what's sold in Europe and the UK. Then let the market decide. The cars can be sold specifically to use this type of Diesel (that they already use in Europe)

If it makes sense the new fuel will replace the old one that the big trucks use now, or if not then both will be sold.

They have. For the last 5 years or so ULSD (ultra low sulfur diesel) has been mandatory for all new "highway" diesel engines, is required for the urea-catalytic emissions controls ("Blutec") on modern diesels, and it's what you will find at fuel stations, unless you specifically seek out off-road diesel.

Europe's standard may still be higher, but it has improved here also.

Environmentalists really hated diesels in the 70s and the 80s because "smog" and the particulate matter that diesels produce was the big scary thing.

Yes, because during the 70s and 80s smog was a really scary thing. You know the problems China has today? Well, now you understand the direction California was headed in the 70s.

Of course, it's pretty easy to look back, now, and deride the politicians of the day, but you also aren't experiencing lung cancer and birth defects because they headed off the issue by enacting laws that have protected you for the last 30 years.

Now gas milage is the big desire but the emissions standards make that nearly impossible.

That's BS. TDI diesels (edit: burning ULSD) are, today, every bit as clean as gasoline cars and significantly more fuel efficient, while operating in a wide range of climates.

80s Tercel got 40MPG 2014 Rav4 gets 20MPG Same gasoline, both 4 cylinder. The RAV4 is much more advanced.

It's emissions that have killed gas milage.

To compare a 1.3 or 1.5 liter engine making well under 90 HP to a 2.0 or 2.5 liter engine making 150-170 HP and saying "both 4 cylinder" like they are the same engine is disingenuous at best.

Combine that with the fact that the modern car is probably 1000 pounds heavier (as well as much taller) it's very obvious where the fuel mileage has gone.

The 80s Tercel weighed something like 900 kg, while an RAV4 weighs 1150 kg. This also has an impact.

And the RAV4 has many more goodies that eat electricity - and did the Tercel even have aircon? Yes, the catalyser burns some fuel, but it is not the only thing there.

The biggest thing probably is that the RAV4 is much more powerful, and in the measurement cycle, the more power there is in the engine, the more of it is used, so the nominal consumption goes up. And to some extent this happens in real life as well. Modern cars are quite overpowered for the actual purposes of transport. Power is nice, because you can feel it when you kick the gas pedal. But that does eat fuel.

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In the U.S. the major benefit to Diesel is torque.

You should try comparing diesel and gas models as equally equipped as possible and see what the cost per mile is.

I just bought a 2.5L Subaru Outback, if we had the 2.0L diesel version I would save about $500 over 100,000 miles.

That's not great in my book. Would I buy a diesel Tacoma if one was available? Yes. So I'm a diesel fanboy, but the economics are closer than we think.

> That's BS. TDI diesels (edit: burning ULSD) are, today, every bit as clean as gasoline cars and significantly more fuel efficient, while operating in a wide range of climates.

That is simply untrue. Even modern diesel engines today produce a ton of extremely fine particulates (PM0.1 or <= 100nm) which are exceptionally carcinogenic.

PM0.1 will happily lodge deeply into your lungs, pass through cell membranes, and lodge into your organs and brain. They've been shown to trigger heart attacks, cause asthma, lung cancer, cardiovascular disease, birth defects and more.

Then there is the huge amount of NOx produced by diesel which causes smog and ground level ozone. Neither is particularly good to breathe. There is a reason why many cities in Europe like Paris are in the process of or thinking about banning diesel cars from their roads.

This does not happen with petrol.

This so-called "smog" is a real thing and it's the number one pollution problem in California. It's not environmentalists that have a problem with smog. It's most people that live in California.
UK/US mileage numbers are different because US gallons (3.8 liters) are smaller than Imperial gallons (4.5 liters). http://en.wikipedia.org/wiki/Gallon

If you are looking at liters per 100KM then they should be equivalent.

What kills me is the Honda I had back in the late 90s (a 1991 CRX HF) that got nearly 50mpg. Why can't they do that kind of fuel efficiency nowadays? Even the "Smart" Fortwo doesn't come close[1], and it's much smaller and lighter. I don't understand how we've gone backwards in fuel efficiency when we've made so many advances in other areas of automotive innovation.

[1] http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=7474&id...

And yes, comparing a 25 year old Honda to a one year old Kei car is a bit apples and oranges, so here's the CRX HF's spiritual successor, which surprisingly gets about the same MPG as the diminutive "Smart" car despite being a hybrid:

http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=7474&id...

Because that little Honda CRX was a tiny little thing that only required a small motor to be drivable. Compare size and all the creature comforts and nifty automatic systems in modern cars. Despite advancements in materials technology, all that stuff still comes with a weight cost, and that weight cost can swamp the efficiency gains of modern engines.
Except the 1991 CRX weighed 1967 lbs and had a 72HP engine, whereas the Smart Fortwo weighs 1653 lbs and has a 101HP engine. By your own theory, the lighter, more powerful car should get better, or at least equal MPG. But that's not the case.
Manual transmission in the CRX vs an auto in the smart?
Clutchless manual in the Smart. I looked at getting one a few years back, but I couldn't justify $15k for a two-seater with almost no breathing room and storage space versus $12k for a Nissan Versa with nearly the same MPG and a huge back seat area/storage area. I simply don't understand how they can justify $15k for what boils down to $9k worth of car. It's all hype.
Yeah, I was "window shopping" and was stunned at the prices they are charging for a car that's probably half of what you get with a Fit or a Yaris. I don't understand their model. Lifestyle car maybe?
I think the attraction with the Smart series is two things. One, it's meant as a city car, so it makes sense for someone in a fully urban area who needs something easy to park. Two, it is pretty much a fashion statement: "Look at my tiny Kei car!"

Now, the second thing is purely subjective and if you want a car based on popularity or "being different", more power to you. Here in the deep south, we have guys and gals who buy the biggest, baddest pickup truck they can...and never haul a thing in the bed for the life of the truck. Pure status symbol. I can imagine a similar mindset among the local twentysomethings wanting to stand out from the crowd by driving an equally impractical car.

This is my idea of a truly smart car, and with a sensible price:

http://www.eliomotors.com/

Aerodynamics. Low and long is much slippier than the relative barn door shape of the smart.
It was my understanding that California's CARB emissions standards were specifically written to keep foreign diesel vehicles off CA roads.
They were specifically written because LA was an unlivable smoggy hell. Diesel particulates and ground level ozone was killing people and causing everything from asthma to cancer.

I was regularly told to stay indoors growing up in LA. You still get a couple dozen smog days a year, but only a couple extreme days. That is way down from the 150-200 days of extreme smog a year that forced me indoors as a kid.

As a soon-to-be resident of LA I'm very glad to hear that the smog situation is much improved.
Probably, like so many other things in our culture, because the multi-national corps. ran the numbers and came to the conclusion that the profit margin would be higher for gasoline, and then did whatever needed to persuade consumers to steer away from this technology.

What else could explain how GM produced those engines?

Although I try to steer clear from hardcore conspiracy theories, sometimes it really is that simple.

I think a perfect explanation is that GM was incompetent and complacent.
Right...ok that's a valid corollary to Occam's razor and I respect that POV.

It just odd, to me at least, that with such a logical and profitable path laid before them, as the article reminds, that GM could be that incompetent when it came to diesel.

You really think there was absolutely no bean-counting influences when it came to the development of diesel at GM?

Bean-counting may well have been a contributor to that incompetence.

Incompetence is not restricted to GM, of course. American cars in general have a pretty bad quality reputation in Europe.

It was the late 70's/early 80's and everything the big three made at the time was garbage. They still managed to sell over a quarter million of them in 1981, though. Nearly as many As Honda sold Civics last year.
A little late for that. Tesla`s Model 3 is coming in 2017, and as great as diesels are, it won`t hold a candle to the efficiency of a pure electric drivetrain. Tesla`s supercharger network will be vast by then, so range won`t be a problem either.

A place like Canada could use diesel, due to our brutal winters, but most of the USA is basically tropical in comparison. Electrics just make sense there, because of the weather and the automobile culture in general.

The age of the fossil fuel personal car is entering its last decade.

From a performance perspective you're right, but it will be quite awhile before Tesla's making cars that are cost-competitive with the currently manufactured Diesels.
Nonsense. Modern diesel passenger cars can approach 1000 miles range on a tank of fuel. Tesla is nowhere close to that and probably never will be.

And I'm talking about nice cars, too. Not tin cans.

http://www.autoblog.com/2010/05/25/bmw-320d-goes-over-1-000-...

Right. Remember that saying about underestimating the bandwidth of a station wagon loaded with magnetic tape?

Same applies to vehicle fuels. Do not underestimate the energy density of a conventional liquid container filled with hydrocarbons.

> Ford decided to drive from England to Munich and back to see how many miles he could squeeze out of a single tank. To extend the drive, Ford kept the windows up and the air conditioning turned off, but otherwise drove about 65-70 mph on the motorways and autobahns. By the time the tank ran dry, Ford had covered 1,013 miles and got to within 70 miles of Calais on the return route. That's an average of 57.4 mpg at 59.3 mph.

Since when do drivers optimize for max miles per tank of fuel? 57.4mpg is extremely low compared to a Tesla's 97mpge [1]. Diesels are great, they just won't make sense when the 35,000$ Model 3 comes out.

1. http://www.fueleconomy.gov/feg/bymodel/2013_Tesla_Model_S.sh...

>>The age of the fossil fuel personal car is entering its last decade.

I wouldn't be so confident. Right now, Tesla addresses a small portion of the expensive sports sedans segment in a few lucky parts of the world. Even then, Tesla cannot make enough cars to fulfill demand. The grid as it is, cannot handle a sudden and drastic increase in demand for electricity and the additional infrastructure needed will be neither cheap nor easily obtained.

I do think the internal combustion engine (w.r.t. to cars) will be relegated to history, but I won't think the transformation will be quick or easy.

> range won`t be a problem

If you don't mind having half an hour break every 200 miles, and only drive 60mph. Day to day it wouldn't bother me at all, but for long drives gas is far superiour.

You won't need to drive 60MPH. Model S owners don't do that now, and the 3 won't change that.

A reasonably short break every two or three hours is something you should be doing regardless of your car's range.

I have yet to have the pleasure in mine, but other Model S owners report that long trips are much more enjoyable than in gas cars, because the quiet, smooth ride reduces fatigue, and the breaks are spaced where you'd want them anyway. The only problem right now is that the charging network isn't fully developed. A common complaint goes something like, "I really wish I could take my Model S for this long trip, but there's a gap in such-and-such place, so we have to take an ICE car instead." I don't think I've seen one person say that they made a trip on electricity but wish they had had a gas car instead.

I'm worried by the diesel we have, let alone a rush to further adoption. I think medical research has a way to go before it educates us fully on what inhaling all that <= PM2.5 is doing to us. The stuff has been found inside our blood cells. Can't imagine anything good coming of that.

I'm skeptical that any filtration system is going to solve that problem. All of the practical systems I've read about either allow a substantial amount of small particulates through, or require some kind of regular maintenance which will screw the rest of us when it's not done.

If we were serious about all of this we (in the US) would convert our heavy duty truck fleet to natural gas. I read one study stating that this would reduce our oil usage by 20%, which would be a strategic accomplishment. The air quality improvement would be a welcome byproduct.

I'm a Canadian, but this article equally applies to us. I've been waiting for years now for Mazda or Subaru to bring one of their diesel cars to Canada. Now and then you see articles like this [1] in the Canadian press celebrating that we will soon have diesel cars in Canada, but it never seems to happen. I had really high hopes when Mazda announced they were bringing the Skyactive-D to Canada for the end of 2013, but there has been nothing but delays since [2].

I spend some time in Korea for work and always drive diesel rental cars and modern diesels are great. I once almost filled one with gasoline because I didn't even realize it was diesel until a Korean co-worker corrected me.

In the end its probably very good for my pocketbook as I've just kept driving my 10 year old Mazda 3 and waiting for the diesels that never arrive.

[1] http://www.theglobeandmail.com/globe-drive/auto-shows/north-...

[2] http://www.forbes.com/sites/dalebuss/2014/01/09/mazda-delays...

When I got my last car if I could have gotten the Euro-diesel version (which supposedly gets > 50MPG vs. the American petrol version getting 30-something) here in the states I would have. I don't have anything against diesel, I've just never seen it offered on anything outside of a truck, let alone a budget subcompact.
I'd love to get one of the Subaru Diesels that are sold overseas.
They won't import their very cool Boxer Diesels because they don't meet California's (and a few other states that follow CARB) draconian emissions requirements. CARB is hostile to diesel. Yes there are 45+ other states they could sell them in but California is the biggest car market and if they can't sell there they won't bother.
Curiously in Germany Diesel is actually cheaper than regular gas at the gas station. This is because it's taxed differently. So a Diesel car saves Germans money two times (less fuel consumption and less price per tank) as compared to a gas engine car, which is why they are extremely popular over here.

That said, on an absolute level in Germany Diesel is still about 1.7x more expensive than Diesel in the US and about 2x more expensive than gas in the US.

Same case currently in India, where petrol is heavily taxed and diesel is subsidized (Ostensibly as a farmers subsidy to run irrigation pumps but also because diesel prices are strongly tied to price of essential commodities). Price per litre is about 1 usd for petrol and 80 cents for diesel. This might change in the future as the current govt. seeks to end diesel subsidies.

Also, It should be noted that the Total Cost of Ownership benefits is not clear cut. Diesel generally has higher Miles per gallon rating, and is cheaper in some countries like India. But diesel engines are more expensive to make, maintain (bills for routine service are higher) and do require a expensive rebuild after a few hundred thousand kilometers (Newer diesel engines have got much better in this regard).

On a side note, it is quite hard to find hard data on the true TCO of cars that can help consumers make a decision.

Even with their great low end torque, diesels do not have the raw acceleration that gas cars do. For American roads and driving styles, horsepower rules.
How many americans let their car go past 4k rpm regularly? Those are the only people that wouldn't benefit from a diesels power curve. Though modern gasoline engines with a turbo is pretty close to the same experience.
Diesel is more expensive than gas.
Not everywhere and not all the time, especially not considering a 30% better mpg, as the article mentions.
I'm confused about the state of diesel engines. There were a few documentaries about the health issues caused(Japan banned diesel entirely). Also the politics putting these issues under the rug (France government massive subventions would be a public shame if they generated illnesses). Meanwhile reading Wikipedia, it says that modern diesel engines are heavily filtered and not toxic.
Same here. IIRC France used to embrace diesel until recently, when they realised particle pollution was difficult to prevent.
I google 'banned diesel' and found contradictory news articles spanning a decade.

Tokyo did ban diesel long ago, but in 2012 there were discussion about allowing them again. France is now trying to avoid them. Knowing about Japan I thought it made sense (with a little big companies / lobby / plot feeling), but now it seems a misguided attempt at being eco-friendly.

Diesel is still a dirty fuel and has done a lot of health damage in Europe. The US has lucked out of this one. See e.g. http://www.channel4.com/info/press/news/the-great-car-con-ch...
>Diesel is still a dirty fuel and has done a lot of health damage in Europe.

Gasoline is also a dirty fuel that does a lot of health damage, but the particles in the exhaust are much smaller and less visible, so people mistakenly assume it's cleaner and better than visible Diesel smoke.

Gasoline is arguably worse, since the tiny invisible particulate matter in the exhaust can stay airborne much longer than the larger, heavier particles in Diesel exhaust.

It is an interesting question but at this point, I hope we skip this iteration and just move into electric (obviously barring large trucks were electric is a little less feasabily at the moment).
Actually, not really. Large trucks could work like trains have for the past several decades: diesel generators produce electricity, which powers electric engines what propel the train.
I wonder why CNG[1] is not that popular in other countries. It is very cheap, it can be installed on any car (gas and even diesels) and AFAIK it produces less pollution.

"CNG may be found above oil deposits, or may be collected from landfills or wastewater treatment plants where it is known as biogas[2]."

In Argentina most gas stations have Petrol and Diesel and I'd say ~60% of them have also CNG. It is very easy to find a CNG station on cities, but harder on rural areas.

[1]: http://en.wikipedia.org/wiki/Compressed_natural_gas

[2]: http://en.wikipedia.org/wiki/Biogas

CNG has a low power density.
The military uses a lot of CNG-converted vehicles when civilian vehicles are needed (all the things you think of as a military vehicle is diesel, but there's a lot of little sedans and big vans for people who need to drive off-base for work). The government can get away with this because military bases are pretty much self-contained and you can put as many CNG fueling stations in as you want to. As I recall, though, the range between fill-ups is terrible compared to gasoline and once you got off base there was pretty much nowhere to fuel the things.
There are a few CNG filling stations around my town (in the US). I believe a few organizations use CNG in some of their vehicles (a cab company and VA shuttles come to mind), but I rarely see vehicles filling at those stations.
Simple, diesel costs more per gallon, it's not as widely sold compared to gasoline (not every station may have it), and there are less car models availavle with diesel as an option. Therefore, even if you just look at it statistically there will be less diesel cars on the road in the USA.
Diesel has more power/volume. In Europe, it also costs less.