Trump Administration Finalizes Major Fuel Economy Rollback, Slashing Targets to 34.9 MPG Through 2031

The Department of Transportation has finalized a sweeping overhaul of federal fuel economy regulations, unwinding Biden-era mandates to prioritize consumer vehicle affordability and market flexibility.

WASHINGTON — The Trump administration on September 28 finalized a landmark federal rule significantly lowering Corporate Average Fuel Economy (CAFE) standards for passenger cars and light-duty trucks through the 2031 model year. The action fulfills a signature deregulatory campaign pledge and dismantles aggressive efficiency benchmarks enacted under the previous administration.

Under the new standard, branded by the White House as the “Freedom Means Affordable Cars” initiative, the projected fleetwide fuel economy target is established at approximately 34.9 miles per gallon by 2031. That represents a dramatic downward recalibration from the 50.4 mpg fleetwide benchmark finalized by the National Highway Traffic Safety Administration (NHTSA) in June 2024.

Transportation Secretary Sean Duffy announced the completed rule during a briefing in Washington, stating that the prior benchmarks functioned as an unlawful regulatory mandate designed to force automakers into electric vehicle production before charging infrastructure, battery supply chains, and consumer demand were prepared to support it.

“Federal regulators should not be using arbitrary fuel standards to pick winners and losers in the automobile showroom,” Secretary Duffy said. “By aligning fuel economy targets with engineering reality, we are protecting consumer freedom, preserving consumer choice in internal combustion engines, and taking direct federal pressure off sticker prices for working American families.”

Core Provisions and Scrapping of the EV Credit Loophole

The revised NHTSA regulation modifies compliance standards across model years 2022 through 2031, altering the economic baseline for domestic and foreign automakers operating within the American market. Crucially, the rule enacts structural reforms that prevent manufacturers from using compliance credits to mask production deficits:

• Credit Trading Phaseout: The rule eliminates the inter-manufacturer CAFE credit trading system starting in model year 2028, halting a lucrative market where dedicated EV manufacturers sold regulatory credits to traditional automakers.
• Fleet Classification Updates: Beginning in 2030, the framework revises the light-duty vehicle footprint model, granting manufacturers greater flexibility in engineering popular crossover, SUV, and light-truck platforms without triggering punitive civil penalties.
• Affordability Impact Estimates: The Department of Transportation projected the regulatory rollback will save American consumers between $1,000 and $1,400 on the purchase price of an average new vehicle by reducing compliance compliance costs absorbed by original equipment manufacturers.

Automotive manufacturing associations offered guarded praise for the announcement. Industry representatives noted that while long-term regulatory certainty is critical for multi-year vehicle design cycles, the 2024 Biden standards had pushed the domestic fleet toward penalties that threatened domestic factory investment.

The Economic and Energy Policy Battle

The decision marks a central pillar of the administration’s broader domestic energy dominance agenda. By lowering fleetwide fuel efficiency requirements, federal regulators expect domestic petroleum consumption to stabilize rather than experience the steep contraction projected under rapid EV transition models.

Energy analysts note that while the move shields automakers from billions of dollars in impending non-compliance fines, it sets up divergent regulatory environments between federal rules and states that adhere to California Air Resources Board (CARB) emission guidelines. Automakers now face the complex task of navigating a fractured national market unless federal preemption litigation resolves state-level enforcement powers under the Clean Air Act.

Immediate Pushback and Legal Challenges Ahead

Environmental organizations and consumer advocacy groups voiced fierce opposition within hours of the rule’s publication. Critics argue that stalling the fleetwide average at 34.9 mpg—a level already within reach of modern fuel-injected engines—will impose long-term costs on drivers at the pump while accelerating greenhouse gas emissions.

Legal counsel for the Center for Biological Diversity and allied environmental coalitions signaled immediate plans to challenge the rule in the U.S. Court of Appeals for the District of Columbia Circuit. Challengers contend that NHTSA violated the Energy Policy and Conservation Act (EPCA), which statutorily requires the federal government to set fuel economy standards at the “maximum feasible” technological level.

With the rule officially published in the Federal Register, the battle over America’s automotive future shifts from agency rulemakers to the federal appellate courts, establishing a high-stakes legal contest that could reach the Supreme Court before the end of the 2027 judicial term.

Historical Precedents: The 2020 SAFE Rule and Legal Parallels

The current regulatory shift mirrors the legal battles fought during the first Trump administration over the 2020 Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule. That earlier standard lowered Obama-era annual efficiency improvement mandates from approximately 5 percent annually down to 1.5 percent, sparking protracted multi-circuit litigation between federal agencies and a coalition of twenty-three states led by California. While the Biden administration subsequently reinstated and heightened those mandates in 2022 and 2024, the legal landscape has since undergone a structural transformation following recent Supreme Court administrative law rulings that dismantled Chevron deference.

Under the emerging doctrine governing agency power, federal appellate judges are now empowered to scrutinize whether NHTSA and EPA exceeded clear statutory boundaries established by Congress under the Energy Policy and Conservation Act. Administration attorneys believe this altered judicial climate provides a substantially stronger legal foundation to defend the 34.9 mpg standard against legal challenges from environmental groups and state attorneys general.