The US has some of the lowest gas taxes and prices in the world. A gas tax would closely follow the "user pays" principle, since, in general, vehicles that weigh more and cause more damage to infrastructure also use more gas. While some hybrid and electric vehicles would pay less for the same use of infrastructure, that would be a good thing since they would be rewarded for causing less air pollution. The key is for government not to become dependent in the long term on the gas tax for funding infrastructure, as the additional cost of gas will accelerate the trend toward more fuel efficient vehicles, thus reducing revenue from the gas tax. It's a good measure that will help fund infrastructure in the near term.