GAO suggests using GPS to track electric vehicles for taxation (gao.gov)

GAO believes road surface maintenance should be paid relative to damage inflicted by travelling on it. Currently revenue for resurfacing is raised mostly by fuel taxes. Heavy commerical trucks are not found to be paying their fair share for the damage they inflict due to loaded weight and high-efficiency hybrids and electric vehicles pay much less and nothing respectively.

GAO suggests a pilot study of gathering revenue per mile travelled using mandatory GPS tracking. One interesting consequence I found would be using the data to "meter" use of roadways by time of day to minimze congestion.

Full report [pdf]: http://www.gao.gov/assets/660/650863.pdf