U.S. fuel economy and greenhouse gas standards: What have they achieved and what have we learned?

Corporate Average Fuel Economy (CAFE) Standards are among the longest-running energy regulations in the United States, enduring several decades of changing political winds. First implemented in 1978, they have been adapted over time, responding to lessons learned and changing circumstances. In combination with the more recent vehicle greenhouse gas emission (GHG) standards, they have achieved enormous fuel savings and emission reductions. Until the 2018 proposed rollback, the quality of research and analysis in support of rulemakings improved dramatically with advances in analytical methods, computing power and the resources dedicated to the task. Despite the abundance of fuel economy and related data, there has been no comprehensive assessment of the standards from 1975 to the present. This paper analyzes historical data to assess the real-world impact of the standards, as well as draw lessons about energy and environmental policy design. Cumulatively, fuel economy improvements due to the standards have reduced fuel consumption by well over one and a half trillion gallons, saved consumers trillions of dollars and avoided 14 billion tons of GHG emissions. Our analysis indicates that fuel savings have exceeded the cost of improving fuel economy, traffic safety has improved and the impact on vehicle travel has been small.