Gasoline prices are the lowest they’ve been in a decade, and according to recent data from the Department of Energy, Americans are buying more gas than ever. While low gas prices are good for consumers, they may be troublesome to those who worry about greenhouse gas emissions. Meanwhile, two important federal policies are pushing ahead to decrease transportation sector emissions by increasing vehicle efficiency and the use of renewable fuels: the federal Corporate Average Fuel Economy standards and the US Renewable Fuel Standard (RFS). Both policies have substantial impacts on consumers’ vehicle and fuel choices as well as on their fuel spending.