NHTSA Medium- and Heavy-Duty Fuel Economy Program

Current understanding

To be populated as evidence accumulates.

2026-09-30 — The Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule III for Model Years 2022 to 2031 Passenger Cars and Light Trucks: cross-connection with cafe-fuel-economy-standards: Both are NHTSA fuel economy regulatory programs, with CAFE covering light-duty and the MDHD program covering medium- and heavy-duty vehicles. (novelty: 4)
2026-08-31 — Resetting NHTSA’s Fuel Economy Program: Commercial Medium- and Heavy-Duty On-Highway Vehicles and Work Trucks: Final rule (“Resetting NHTSA’s Fuel Economy Program”) in which NHTSA disclaims statutory authority to set fuel-economy standards for engines alone, limits its program to complete commercial medium- and heavy-duty vehicles/work trucks, and immediately halts enforcement of engine-only standards pending a rewrite. (novelty: 3)