Corporate Average Fuel Economy standards require automakers to meet a minimum average fuel efficiency threshold for the vehicles they manufacture and sell in the United States. Despite these standards being first enacted in 1975 as part of the Energy Policy and Conservation Act, they remained essentially unchanged until the Energy Independence and Security Act of 2007.[1] There is now renewed interest in the standards, and now is a good opportunity to evaluate their effectiveness. This study uses the latest available data to better estimate the costs and benefits of CAFE standards and explores whether fuel economy can be improved in a more economically efficient way.