The National Highway Traffic Safety Administration (NHTSA) published a final rule September 30 amending federal fuel-economy standards for new passenger cars and light trucks for model years 2022 through 2031. It takes effect November 30, 2026.
What the standards say
The standards are size-based formulas, so NHTSA gives industry-wide averages as estimates. It puts the average required level for model year 2031 at about 34.9 mpg (40.2 for passenger cars, 26.4 for light trucks), against about 49.3 mpg under the 2024 standards. NHTSA says the earlier standards counted electric vehicles and compliance credits (earned by beating a standard), which it says federal law bars it from considering; the new levels rest on gasoline and diesel vehicles.
NHTSA lists an estimated achieved fleet average of 35.4 mpg for model year 2024 and projects 40.2 for 2031. It says real-world fuel economy is generally 20 to 30 percent below required levels.
From model year 2030 the rule redefines light trucks, and it ends trading between automakers of credits earned from model year 2028.
What NHTSA estimates for prices and fuel
All figures are NHTSA's estimates.
- Up-front cost. Average per-vehicle regulatory cost for model year 2031, which with no fines in force is technology cost only: $949 under the final standards, $2,238 under the 2024 standards. If automakers pass the savings on, NHTSA says, new-vehicle costs would be $1,289 lower on average that year.
- Fuel use. Gasoline use from 2024 through 2050: 2,761 billion gallons, 122 billion (4.6 percent) more than the 2,639 billion under the 2024 standards. NHTSA projects fleetwide use still falls over time under every alternative it considered.
- Fuel spending. For vehicles built through model year 2031, at a 3 percent discount rate (which converts future dollars to today's value), NHTSA lists $60.6 billion in forgone fuel-cost savings and $51.8 billion in lower technology costs (2024 dollars) compared with the 2024 standards. Overall, it estimates net benefits to society of about $41.8 billion.
Some commenters noted that for some model years the average lifetime rise in fuel costs is greater than the average drop in projected vehicle price. NHTSA responds that once other private costs and benefits are counted, both private and overall net benefits are positive.
Who it covers and the dates
NHTSA says the rule affects companies that make or sell new cars and light trucks. The notice lists no buyer action.
The proposal was published in the Federal Register December 5, 2025; its comment period ended February 4, 2026, with 68,294 comments, NHTSA says. The final rule's dates section gives only the November 30 effective date, no new comment period. Documents: regulations.gov, docket NHTSA-2025-0491.
What it does not say
The cost estimates assume automakers pass savings on and try to comply wherever practicable, though federal law now sets the civil penalty for missing a standard at $0 (Public Law 119-21). NHTSA says actual manufacturer responses may differ from its simulations, and that emissions of various pollutants would be higher than under the 2024 standards, by amounts it calls nominal.