As reported in Commercial Carrier Journal, the Environmental Protection Agency will proceed with the 2027 timeline for its heavy-duty NOx rule—currently set to take effect with the 2027 model year—but says changes are in store.

The American Trucking Associations, National Tank Truck Carriers, Truckload Carriers Association, and 49 state trucking associations in August 2025 sent a letter to EPA, asking the agency to delay implementation until 2031. The request cited "substantial compliance costs and operational burdens at a time when the trucking industry is already contending with historically difficult market conditions."

EPA now reportedly intends to issue a final rule in spring 2026 that will go into effect for the 2027 model year but indicated that any final rule could have major changes from the Biden Administration proposal.