With CAFE standards approaching and fuel economy rising across the U.S. fleet, states are feeling the heat as revenue from gasoline, taxed per gallon, continues to dry up.

States have limited avenues to pursue an increase in funding, and many thoughts of the subject are that states would charge motorists based on their miles traveled. This is perhaps the only way to maintain road funding as fuel efficient vehicles require less gallons, and thus feed the state less income.

According to a USA Today article, a few states are already testing programs that would do just that. Oregon and Minnesota are currently in the testing phase of a program that would essentially be pay-per-mile, with different approaches to tracking mileage. Washington and Nevada are also looking at similar ideas.

Such new ways to derive income may be necessary as budgets for transportation continue to fall and more roads go into a state of disrepair. The federal gasoline tax, at 18.4 cents per gallon, hasn't been touched in decades. A similar situation holds true for many individual states as well- gasoline taxes in most states haven't been touched for years or even decades in some states, and falling gasoline demand as fuel efficiency improves, is causing transportation budgets to fall.

The USA Today article also mentions that folks, rather unsurprisingly, are quite resistant to government GPS boxes in their vehicle, citing the vast privacy issues that could be opened with such a device. Although some drivers have allowed insurance companies to place boxes in their vehicle to detrmine their rates, privacy concerns that many share is keeping this possibility very remote.

According to USA Today, "Other options being considered: People who don't want to use technology may be able to pre-pay for a certain amount of miles or buy an unlimited amount of miles with a flat annual tax.

In Minnesota, 500 volunteers in largely urban Hennepin and mostly rural Wright counties have been testing a system using software installed on smartphones, says Chris Krueger, spokeswoman for the Minnesota Department of Transportation. "We can collect trip info and be able to simulate what it would be like to have a mileage-based user fee," she says."

So what do you think? Are you willing to pay-per-mile for better roads?