OAKLAND — California Attorney General Rob Bonta led a coalition of 26 states, counties, and cities in filing a lawsuit against the National Highway Traffic Safety Administration on October 2, 2026. The legal action challenges the agency's final rule weakening corporate average fuel economy standards for new passenger cars and light trucks.

The suit was filed in the U.S. Court of Appeals for the First Circuit. The coalition includes Arizona, California, Colorado, Connecticut, Delaware, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, New Mexico, New York, North Carolina, Oregon, Rhode Island, Vermont, Washington, Wisconsin, the District of Columbia, the City of Chicago, the City and County of Denver, the City of New York, and the City and County of San Francisco.

The complaint alleges that the National Highway Traffic Safety Administration's new standards for the next five years require less efficiency than the U.S. fleet achieved in 2021. It further asserts that the agency ignores millions of electric vehicles in the existing fleet when setting standards. The lawsuit alleges that the agency fails to set standards at the maximum feasible level required by Congress.

The filing argues that the National Highway Traffic Safety Administration's final rule is arbitrary and capricious and violates the Administrative Procedure Act and the Energy Policy and Conservation Act. The lawsuit alleges that the rule obscures nearly $220 billion in lost fuel savings for drivers. It also claims the agency refuses to consider hundreds of billions of dollars in future damages from climate change-driven disasters. The complaint states that the rule will end the corporate average fuel economy credit trading program in 2028.

Bonta criticized the administration's approach in an official statement. "The President started a war that has created volatility in oil markets, disrupted global energy supplies, and left families and businesses paying the price at the pump," Bonta said. "Yet, the Trump Administration is attempting to gut fuel economy standards and force Americans to spend billions more on gas while poisoning the air in our communities."

Why It Matters

The lawsuit filed by California Attorney General Rob Bonta and the coalition affects the residents of the 26 states, counties, and cities involved, as well as consumers in the United States who are impacted by the weakened fuel economy standards. The allegations center on significant financial and environmental impacts, including nearly $220 billion in lost fuel savings for drivers and hundreds of billions of dollars in unconsidered future damages from climate change-driven disasters.

This legal challenge fits into a documented pattern of regulatory shifts and litigation regarding vehicle efficiency. The Court of Appeals for the District of Columbia Circuit has historically been a key venue for challenges to federal agency rulemaking, including cases involving NHTSA’s CAFE standards. The current rule allegedly repeats precedents set by prior legal challenges, such as a 2022 ruling that found earlier standards violated the Administrative Procedure Act by failing to adequately address climate change impacts.

Timeline

On October 2, 2026, California Attorney General Rob Bonta led a coalition of 26 states, counties, and cities in filing a lawsuit against the National Highway Traffic Safety Administration. The lawsuit challenges the National Highway Traffic Safety Administration's final rule weakening corporate average fuel economy standards for new passenger cars and light trucks. The lawsuit alleges that the National Highway Traffic Safety Administration's final rule is arbitrary and capricious and violates the Administrative Procedure Act and the Energy Policy and Conservation Act. The lawsuit alleges that the National Highway Traffic Safety Administration's rule will end the corporate average fuel economy credit trading program in 2028. The lawsuit alleges that the National Highway Traffic Safety Administration fails to set standards at the maximum feasible level required by Congress. On that same date, he stated, "Yet, the Trump Administration is attempting to gut fuel economy standards and force Americans to spend billions more on gas while poisoning the air in our communities." He also said, "Let’s be clear: The Trump Administration is doing this to line the pockets of their Big Oil donors." He added, "California will not stand idly by, we will defend fuel economy standards that keep costs down, protect public health, and build a better, sustainable future."

What's New

Reports also indicate that the Trump Administration's 2019 SAFE Vehicles Rule faced criticism for not adequately considering the impact of electric vehicles on fleet-wide fuel economy, which is one of the claims in the current lawsuit against NHTSA.

Further background shows that in 2020, the first Trump Administration finalized the Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule, which revoked California's Clean Air Act waiver to set state-specific greenhouse gas standards, establishing a single national fuel economy framework. In 2019, the Trump Administration finalized the Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule, which rolled back CAFE standards and reduced the stringency of fuel economy requirements for model years 2021–2026, leading to legal challenges over its compliance with the Energy Policy and Conservation Act. It was also noted that judicial challenges to NHTSA's CAFE rules must be filed in the U.S. Court of Appeals for the District of Columbia Circuit, as specified in the 2019 SAFE Vehicles Rule preamble, despite the lawsuit in this case being filed in the First Circuit. Additionally, under the Administrative Procedure Act (APA), agencies like NHTSA must base their rules on reasoned decision-making and cannot act arbitrarily or capricious, which is one of the central allegations in the lawsuit against the new CAFE standards.