Sierra Club is opposing a proposal by the National Highway Traffic Safety Administration (NHTSA) that would weaken fuel economy standards for new passenger cars and light-duty trucks (SUVs, pickup trucks, minivans, etc.). On February 4, 2026, Sierra Club and partners submitted extensive comments and technical analysis opposing NHTSA’s sweeping rollback of the Corporate Average Fuel Economy (CAFE) standards, a critical tool for reducing pollution, saving money at the gas pump, and protecting public health. Motor vehicles are the largest source of greenhouse gas emissions in the United States and a major source of harmful soot and smog-forming pollution as well.
The CAFE standards were originally established in 1975 to incentivize American innovation to conserve fuel and strengthen national security by reducing America’s dependence on foreign oil. The CAFE standards require car manufacturers to make their vehicles more fuel efficient every year, which not only reduces dependence on foreign oil, but also reduces pollution and saves drivers money on fuel. The CAFE standards are calculated as an average across a manufacturer’s whole fleet of vehicles, which means that electric vehicles and hybrids—which use little to no fuel—help boost the manufacturer’s overall fuel economy average and allow them to sell less efficient vehicles like trucks and SUVs while still meeting the requirements. Under President Biden, NHTSA significantly strengthened these standards to achieve a projected fuel economy of 50.4 miles per gallon (mpg) in model year 2031, saving yearly between 64 and 115 billion gallons of gasoline, cutting more than 650 million metric tons of carbon dioxide emissions, and reducing costs by approximately $250 to 400 per vehicle through fuel savings at the pump.
The Trump NHTSA’s proposed U-turn would drastically weaken standards. For example, instead of achieving the 50.4 mpg goal by 2031, as previously planned, the rollback would lower the target to 34.5 mpg by 2035, which is even worse than what Congress required automakers to achieve in 2020. The comments submitted by Sierra Club and partners point out why this rollback is not only harmful but illegal in the following ways:
- NHTSA’s proposal covers ten model years, even though the law limits CAFE rulemakings to five model years at a time.
- It applies the new rules retroactively to historic model years, which manufacturers can’t change.
- NHTSA’s own modeling data projects that manufacturers would significantly overcomply with the new standards, going against the requirements for the CAFE standards to be set at the “maximum feasible” level, meaning the highest level that balances what is technologically and economically possible.
- NHTSA’s proposal bars trading of compliance credits between automakers, which serves no statutory purpose, and specifically targets an important source of revenue for electric vehicle-only manufacturers, who overcomply with the standards.
- NHTSA also double counts the cost-savings, claiming that automakers would pass through the cost-savings to customers and also reinvest the cost-savings in other non-fuel economy-related features that customers allegedly value more highly.
NHTSA must now review and respond to Sierra Club’s comments and we will be closely scrutinizing the final standards to hold NHTSA accountable to all of its statutory requirements.