EPA Releases Proposed Phase 3 GHG Emissions Standards for Heavy-Duty Engines and Vehicles

On April 12, 2023, the Environmental Protection Agency (EPA) announced its proposed phase 3 greenhouse gas (GHG) emissions standards rule for heavy-duty vehicles beginning with model year 2027. 

Specifically, this rule would apply to heavy-duty vocational vehicles (such as delivery trucks, refuse haulers, public utility trucks, transit, shuttle, school buses, etc.) and tractors (such as day cabs and sleeper cabs on tractor-trailer trucks).

The proposed rule, which would also set further stringent CO2 standards for model years 2028 through 2032, builds upon the 2011 Phase 1 GHG rule and the 2016 Phase 2 GHG rule.  Additionally, the EPA issued a proposed rule that would reduce GHG emissions for light- and medium-duty vehicles.

While the rules have not been published in the Federal Register yet, TRALA anticipates that comments will be due around June 1, 2023.  The EPA plans to hold a public hearing prior to the comment period deadline, which will occur on May 2 and May 3.  A separate hearing on the light- and medium-duty vehicles rulemaking will be held on May 9 and 10. TRALA will work with its environmental consultant and its allies to ensure it fully addresses how these rules will impact its membership.

You may view the proposed heavy-duty vehicle rule in its entirety by clicking here and the light- and medium-duty rule by clicking here.

Please don't hesitate to contact Robby Wehagen at or Elizabeth Hyers at, if you have any questions or need additional information.