Environmental groups challenge US rollback to 34.9-mpg fleet standard

On October 2, 2026, the Associated Press reported that five environmental groups petitioned the US Court of Appeals to review the administration's relaxation of Corporate Average Fuel Economy standards. The revised rule sets an industry fleetwide average of about 34.9 miles per gallon for passenger cars and light trucks in model year 2031, down from a projected 50.4 mpg under the prior rules. Automakers and suppliers should avoid treating the rollback as settled compliance relief because litigation can alter timing, product planning and the interaction between federal standards and state emissions regimes. Counsel should preserve the technical and economic record supporting current fleet decisions so strategy can be adjusted if the rule is stayed, remanded or replaced.