Taxing mileage -- as opposed to trying to raise fuel taxes -- is an idea that's not only raising eyebrows, it's also raising interest. Seven other states are reported to be interested in finding a publicly-palatable way to tax mileage. A panel in North Carolina even recommended that drivers be charged a quarter-cent-per-mile for their year's driving. In such a scenario, after 15,000 miles you'd owe the state $37.50.
Naturally, the hurdles are many and it will be years before we see anything like this happening -- but beware: it's gone beyond "Let's think about it" to "Let's look into this." States envision working with manufacturers to get the standardized mileage-reporting technology installed in cars. In addition to the substantial privacy issues that would raised by such a move, there's a question of whether a flat mileage tax would blunt the move to energy-efficient vehicles -- the gent in the Prius might not be happy about paying the same as the gent in the F-250 Super Duty.