EPA Publishes Phase 3 Greenhouse Gas Standards for Trucks Starting With Model Year 2027

The Environmental Protection Agency's Phase 3 greenhouse gas emission standards for heavy-duty vehicles were published in the Federal Register on April 22, 2024, after EPA announced the final rule on March 29. The rule took effect June 21, 2024, and sets carbon dioxide standards for model year 2032 and later trucks that phase in starting as early as model year 2027 for some vehicle categories.

How the standards ramp up

The rule revises some model year 2027 standards set under the earlier Phase 2 program and then tightens limits year by year. According to the Federal Register notice:

• Light heavy-duty and medium heavy-duty vocational vehicle standards start in model year 2027, 17% and 13% more stringent than Phase 2.
• Day cab tractor standards start in model year 2028, 8% more stringent.
• Heavy heavy-duty vocational standards start in model year 2029, 13% more stringent.
• Sleeper cab tractor standards start in model year 2030, 6% more stringent.

By model year 2032, compared with Phase 2, the standards are 60% more stringent for light heavy-duty vocational vehicles, 40% for medium heavy-duty vocational vehicles, 40% for day cabs, 30% for heavy heavy-duty vocational vehicles and 25% for sleeper cabs.

EPA said the final standards increase in stringency more slowly from 2027 to 2030 than it had proposed. The agency also said the standards "do not mandate the use of a specific technology," and projected a mix of compliance paths including engine, transmission and aerodynamic improvements, hybrids, battery-electric trucks and hydrogen fuel cells.

Transport Topics reported that EPA projected 30% of heavy heavy-duty vocational trucks and 40% of short-haul day cabs would need to be zero-emission by 2032. EPA said it received more than 175,000 public comments on the proposal, TT reported.

The rule also adds warranty requirements for batteries and other zero-emission vehicle components and requires customer-facing battery state-of-health monitors on plug-in hybrid and battery-electric trucks.

Industry pushback

"ATA opposes this rule in its current form because the post-2030 targets remain entirely unachievable given the current state of zero-emission technology, the lack of charging infrastructure and restrictions on the power grid," American Trucking Associations President Chris Spear said. He added that "a successful emission regulation must be technology neutral and cannot be one-size-fits-all."

The Truck and Engine Manufacturers Association said: "We are concerned that the final rule will end up being the most challenging, costly and potentially disruptive heavy-duty emissions rule in history."

The Owner-Operator Independent Drivers Association said the rule effectively mandates that 25% of new heavy trucks sold be all-electric by 2032. "Small business truckers happen to care about clean air for themselves and their kids as much as anyone. Yet this administration seems dead set on regulating every local mom and pop business out of existence with its flurry of unworkable environmental mandates," OOIDA President Todd Spencer said.

Truckload Carriers Association President Jim Ward said the rule "calls for the strictest-ever limits on greenhouse gas emissions from heavy-duty trucks."

What it means for drivers and fleets

The standards apply to truck and engine manufacturers, not to carriers directly, but they shape what fleets will be able to buy. Day cab tractors face the first tractor limits in model year 2028 and sleeper cabs in model year 2030, giving long-haul fleets more lead time than regional and vocational operators. Fleets planning equipment purchases for the late 2020s had to weigh how manufacturers would meet the tighter limits, including the mix of diesel improvements, alternative powertrains and zero-emission models they would offer, along with the charging and fueling infrastructure such trucks would need.