The U.S. Environmental Protection Agency is moving forward 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 (ATA), National Tank Truck Carriers, Truckload Carriers Association, and 49 state trucking associations in August penned a letter to EPA, asking the regulator to push implementation to 2031, citing “substantial compliance costs and operational burdens at a time when the trucking industry is already contending with historically difficult market conditions.”
Administrator Lee Zeldin in March announced that the EPA was reevaluating the Biden-era 2022 Heavy-Duty Engine and Vehicle rule that regulates oxides of nitrogen (NOx) and other emissions beginning with Model Year 2027.
EPA told CCJ the agency continues to reevaluate the rule and plans to propose a rule in the spring of 2026 that will take effect the following model year.
“If finalized,” EPA said, “the action will make major changes to the program requirements while maintaining the Model Year 2027 start of the standards, which can significantly reduce the cost of new heavy-duty vehicles, while still protecting human health and the environment, and avoiding regulatory distortions of the heavy-duty vehicle market.”
A spokesperson for Daimler Truck North America told CCJ Monday that the company appreciates EPA’s efforts to reduce costs while maintaining a focus on air quality and legislative consistency, adding “[This] announcement provides the regulatory certainty needed for effective production planning and customer support.”
The new limits currently tighten tailpipe NOx emissions to a level 80%-plus below the current standard and reduce the particulate matter limit by 50%. The agency also will require that OEMs extend warranties to 450,000 miles from 100,000 and useful life limits to 650,000 miles from 435,000 miles.
EPA did not disclose plans for its 2026 revised proposal, but the extended warranty has been cited by OEMs as a major driver of increased costs for MY2027 trucks. Given that EPA expects its changes to the current NOx regulations to drive down costs, warranty provisions are likely to be affected.
PSR Analysis: It appears the EPA will proceed with the implementation of the Phase 3 GHG emission regulations for medium and heavy vehicles for MY2027. However, they are likely to make significant adjustments to the standards. It is also likely they will eliminate the extended warranty for the MY2027 vehicles thus significantly reducing the up-front purchase price.
While we will not know the final outcome until this spring, it is possible the EPA will maintain the 2027 nitrous oxide emission rule at the 0.035 g/hp-hr standard moving forward from 2028-2032. If the EPA flattens the nitrous oxide rule, it would eliminate the need to transition from ICE engines toward zero-emission vehicles during this period. PSR
Chris Fisher is Senior Commercial Vehicle Analyst at Power Systems Research
