“You have to phase it in, maybe in three-to-five years after a one-time transfer,” he said. “The last time the gas tax was raised, it was part of a big budget bill. You’re not going to get a standalone vote on something like that.”

Representative Sam Graves, of Missouri, the top Republican on the House Transportation and Infrastructure Committee, said a mileage-fee could easily be substituted for the gas tax without using techniques that raise the thorny privacy issues that tanked prior versions of the proposal.

“It can be done right now with the technology that we have,” Graves said last month during an appearance at an American Association of State Highway and Transportation Officials conference.

Pump Formula
Graves suggested that for gas- or diesel-powered vehicles, a per-mile tax can be assessed through a simple formula at the pump. “We take whatever you come with as the national average for miles-per-gallon, multiply that by whatever the VMT is going to come up to, let’s say a penny, and we just calculate it at the pump,” he said.

“It doesn’t take any new technology,” he said. “This isn’t about any GPS tracking devices or anything like that. This is just a formula at the pump very much like we’re doing now with the fuel tax.”

Graves suggested Friday that planned modernization of the U.S. Postal Service vehicle fleet could provide an opportunity to test a mileage fee program on a national scale because the some of new postal vehicles will be electric.

Adrian Moore, vice president of policy at Reason Foundation, a libertarian think tank, said a mileage fee would be a more equitable user fee than the gas tax because drivers of electric cars avoid paying anything. And those who can afford new, more fuel-efficient cars are paying less per mile than their counterparts who drive older cars.

The result, he said, is a system in which “those that can afford new technologies will be privileged to pay less than those who can’t afford it.”

The longest-running U.S. mileage tax program started in 2013 in Oregon, where drivers who join OReGO, as the program is called, are charged 1.8 cents per mile for trips that take place on the state’s roads. Participants are given the option of using a GPS device to record their miles or using a non-GPS option that tracks usage based on the mileage odometers of cars.

In return for participating, the drivers are offered a tax credit reimbursing them for the 36-cent-per-gallon Oregon gas tax that they pay on fill ups. Drivers in the program receive regular statements of their road charges based on the reported miles, which also show their fuel tax credits.