Gas tax on miles, not gallons, tested PORTLAND, Ore., March 25 (UPI) -- Oregon is testing the idea of collecting highway funds through a tax on miles driven, rather than gasoline consumed. Eighty percent of Oregon's highway money comes from its 24-cents-per-gallon gas tax. If the state promotes reducing gasoline consumption and consumers tend to buy the fuel-efficient vehicles, including hybrids, highway revenues would take a hit, The New York Times reported. The test program uses a global positioning system to track miles driven, using a black box to calculate how many miles are clocked in-state, out of state and...