EPA proposes cost-cutting revision to 2027 heavy-duty truck emissions rule

The U.S. Environmental Protection Agency (EPA) has proposed a rollback of certain emissions-system warranty requirements for new heavy-duty trucks, aiming to reduce cost increases for new equipment starting in 2027. The proposal keeps in place the tighter nitrogen oxide (NOx) emission limits scheduled to take effect in January, maintaining an 80% reduction requirement from the current 200 mg/bhp-hr down to 35 mg/bhp-hr. However, it scales back a significant expansion of warranty coverage and delays the implementation of updated useful life extensions. Under the existing 2022 Biden-era rule, the useful life for heavy-duty trucks was set to increase from 435,000 miles or 10 years to 650,000 miles or 11 years, while the warranty period for emissions-related components was slated to expand from 100,000 miles or five years to 450,000 miles or 10 years. The EPA’s proposal would retain the core NOx reduction mandate but reduce the financial burden on manufacturers and operators by rolling back these warranty and useful life provisions. This move is part of the Trump administration’s broader effort to unwind several Biden-era vehicle pollution regulations, including a May proposal to delay emission standards for new passenger cars and lighter commercial vehicles up to Class 3 starting with model year 2027.