The Obama Administration has recently floated the idea of a national mileage tax. The government would install electronic tracking equipment in vehicles to determine how many miles drivers traveled, and drivers would pay the tax electronically at gas stations.
The President proposes creating a Surface Transportation Revenue Alternatives Office costing $200 million through fiscal year 2017, to study how to best implement such a policy. The new office would examine four areas including “the capability of states to enforce payments, the reliability of technology, administrative costs, and ‘user acceptance.'”
I think a mileage tax is a non-starter for several reasons.
See my piece at Big Government for my full argument.