But Washington state is actually losing money because of it and as a result, the state is now considering a "pay-by-mile" tax.
The state predicts gas tax collected today won't add up to enough cash to pay for future road projects.
Drivers of fuel-efficient cars are spending less at the pump, which means they are paying less in gas tax while driving the same amount of miles. So the state is a considering a pay-by- mile tax to even the playing field since as it stands now, drivers of gas guzzlers pay more in taxes per mile than drivers of fuel-efficient cars.
"In the future, as vehicles get more and more efficient, that puts a strain on our ability to maintain and operate our transportation system," said Jeff Doyle of the Washington state Department of Transportation.
A state-sponsored study released this week says a pay-per-mile tax could make up the shortfall, but the study did not lay out how it would work.
Such a tax could be implemented through yearly odometer checks using tolling devices that were tested during a study four years ago, or through a system similar to the existing Good to Go pass.
The state Legislature will be asked to spend several million dollars on another study to find a recommended method.
And Washington state is not alone; 20 states, including Oregon, are considering similar measures.
"This is nothing on the horizon. It's not going to solve our current transportation funding issues, but we need to be prepared for the future," Doyle said.
There is already a tax rate being discussed -- 1.5 cents per mile.
By 2025, the federal government will require new cars to average 54.5 miles per gallon.