Corporate Average Fuel Economy Standards / Greenhouse Gas Standards

The Environmental Policy Initiative is tracking the environmental regulatory rollbacks of the Trump administration. Click here for the list of rules we are following.

Why it Matters

The National Highway Traffic Safety Administration (NHTSA) in the Department of Transportation (DOT) has set fuel efficiency standards since 1975. In a separate but related process, the Environmental Protection Agency (EPA) has issued greenhouse gas emission standards since in 2010. Transportation is the one of the largest greenhouse gas sources in the US, contributing more than one-quarter of all emissions.  Improving the fuel economy of cars saves gas money and lowers emissions; a roll-back of standards increases fuel costs and pollution.

Current Status

EPA is conducting a midterm evaluation for light-duty vehicle greenhouse gas standardsNHTSA has stated it intends to take preliminary steps toward setting 2022-2025 CAFE standards. The agency indicated it will review the existing 2021 CAFE standards as well.


On October 15, 2012 EPA published a final rule setting greenhouse gas standards for passenger cars, for model years 2017-2025, and NHTSA set fuel economy standards for 2017-2021 and forecast standards for 2022-2025.

On January 12, 2017 EPA Administrator McCarthy determined in a “midterm evaluation” that the 2022-2025 greenhouse gas standards remained appropriate and should not change.

Trump Era

On March 13, 2017 the Alliance of Auto Manufacturers petitioned for review of EPA’s evaluation of greenhouse gas standards in the D.C. Circuit.

On March 22, 2017 EPA published notice of its intent to reconsider the midterm evaluation of greenhouse gas standards. EPA stated it would make a new determination by April 1, 2018. (The Alliance of Auto Manufacturers withdrew their petition on March 20, 2017.)

On July 26, 2017 NHTSA published a notice of intent to conduct an environmental impact statement, a preliminary step toward setting 2022-2025 CAFE standards.

On August 21, 2017 EPA opened a comment period for the reconsideration of the midterm evaluation for the 2022-2025 greenhouse gas standards. The comment period was open until October 5, 2017.

For More Information

For more information on the history of both rules see SaveEPA’s pages on CAFE standards and greenhouse gas standards. Also see Columbia University Sabin Center for Climate Change Law’s database for more on both rules. 


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