The roads are maintained using money from the gas tax. When it was implemented, this system made perfect sense; the more you drove, the more money you put into the roads. This was fair because, at the time, just about all cars were rather inefficient. Now people are driving everything from 8mpg Hummers to Nissan Leaves that never get gassed up.
It's clearly not fair that electric car owners and hybrid cars owners don't pay their share, or their full share as the case may be, and so Oregon is looking to add a milage tax for owners of high-efficiency vehicles (55mpg or better). Both a flat rate and a 1.2 cent/mile rate have been proposed.
[via Associated Press]