Biden-era rules projected a combined fleet average of 50.4 mpg by 2031. The Trump administration’s finalized rule, published Sept. 28, sets that target at 34.9 mpg — a reduction of more than 15 mpg that reshapes what automakers must build through model year 2031.
NHTSA’s Corporate Average Fuel Economy program — CAFE — regulates the average efficiency of an automaker’s entire fleet, not each individual vehicle. The new rule takes effect 60 days after Federal Register publication. For car buyers, that gap between the old targets and the new ones will eventually show up in showrooms, at fuel pumps, and on window stickers. The question of the affordable new car sits at the center of that debate.
The Numbers Behind the Rollback
A 15-mpg gap separates the old targets from the new ones — and the math carries real consequences for automakers and consumers alike.
The current fleetwide average sits at roughly 30.1 mpg for model year 2024. The finalized rule projects that rising to 34.9 mpg combined by 2031, with separate targets of 40.2 mpg for passenger cars and 26.4 mpg for light trucks. These are fleet averages: a manufacturer’s entire car or truck lineup must meet the standard collectively, not vehicle by vehicle.
Key changes in the final rule:
- Combined fleet target moves from approximately 50.4 mpg (Biden era) to 34.9 mpg by 2031
- Vehicle reclassification begins model year 2030, closing criteria that allowed some small SUVs to qualify as light trucks; NHTSA projects a regulatory shift from roughly 70% light trucks to 70% passenger cars in fleet composition — a regulatory estimate, not a consumer-behavior forecast
- Intermanufacturer CAFE-credit trading ends for credits earned from model year 2028 onward; previously, a gas-heavy automaker could purchase compliance credits from an EV-heavy manufacturer to satisfy its requirements
- USDOT projects a reduction of approximately $1,300 in average new-vehicle cost — a figure that intersects with the broader reality that the car payment has become a defining financial burden — and $138 billion in aggregate consumer savings over five years — both are agency estimates, not confirmed outcomes
- The administration also projects 1,900 lives saved and more than 300,000 serious injuries prevented, though the time period and methodology for these figures are unspecified in available sources
What It Means for Your Next Car
The credit-trading phaseout removes a key compliance tool — forcing every automaker to meet efficiency targets through its own lineup rather than buying its way to compliance.
Transportation Secretary Sean Duffy called the previous requirements an “illegal mandate” that pushed automakers toward more expensive electric vehicles consumers didn’t want. That characterization is the administration’s stated political position, not an independently established finding. Reuters described the final rule more plainly: a major boost for gasoline-powered vehicles and a clear reversal of Biden-era EV acceleration policy.
The credit-trading phaseout carries structural weight beyond the headline numbers. EV manufacturers such as Tesla and Rivian, which built revenue streams by selling compliance credits to gas-heavy rivals, stand to lose that income stream. Those gas-heavy automakers, in turn, lose a compliance safety valve. Note that previously generated credits and certain internal carry-forward and fleet-transfer provisions remain available — the change targets new intermanufacturer trading from model year 2028 onward, not all existing mechanisms.
Critics are expected to argue the rollback will increase gasoline consumption relative to what Biden’s rules would have required and slow EV adoption. Reuters reporting supports the gasoline-consumption concern. The administration argues the rule delivers affordability and flexibility; USDOT’s own estimates, however, sit alongside Reuters’ projection that lifetime fuel costs could rise by more than $1,600 per vehicle — a figure that cuts against the sticker-price savings. Shifts in gas prices will play a significant role in determining how consumers respond.
By 2031, the projected fleetwide average under the new standards will be measurably lower than Biden’s rules required. Whether that translates to cheaper vehicles at the lot or higher fuel bills over time depends on which set of estimates proves closer to reality — and how often the tank needs filling.
