The Trump administration has put forth a draft rule aimed at undoing the Greenhouse Gas Phase 3 regulation, which is considered one of the most significant remaining Biden-era emissions regulations affecting the trucking sector.
This proposal was jointly unveiled with a statement from Environmental Protection Agency Administrator (EPA) Lee Zeldin, advocating for the repeal of the Endangerment Finding that has enabled presidential administrations to regulate greenhouse gas emissions since 2009.
According to Zeldin, “This proposal signifies the end of 16 years of uncertainty for automakers and American consumers. Feedback from various stakeholders suggests that the Obama and Biden administrations distorted laws, disregarded precedents, and manipulated scientific data to achieve their goals, resulting in hidden taxes amounting to billions of dollars annually for American families.” He emphasized that the emissions standards themselves presented a tangible threat to the livelihoods of Americans, not the carbon dioxide concerns the Finding initially addressed.
The process of repealing greenhouse gas regulations involves a lengthy rulemaking procedure and is likely to face several legal challenges.
Zeldin claimed that nullifying the Endangerment Finding and its related regulations could alleviate over $1 trillion in “hidden taxes” on American businesses and families.
If the proposal is finalized, it would eliminate all greenhouse gas standards established during the Biden and Obama administrations for light-, medium-, and heavy-duty vehicles, including the EPA’s initial regulations for light-duty vehicles launched in 2010 and those for medium- and heavy-duty vehicles initiated in 2011. This would also impact technologies like the start-stop feature on new cars.
What is GHG3?
In 2024, the EPA implemented stringent emissions standards for heavy-duty trucks covering model years 2027 through 2032. This comprehensive final rule mandated that 25% of new heavy trucks sold in the U.S. be zero-emission by 2032.
Zeldin previously announced intentions to reevaluate the Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles – Phase 3 (GHG3) final rule and revisit aspects of the Biden administration’s “Clean Trucks Plan,” which also includes the 2022 Heavy-Duty Nitrous Oxide (NOx) rule.
Jim Mullen, Executive Director of the Clean Freight Coalition, criticized the GHG3, labeling it “unattainable” and asserting it could severely impact the trucking industry, threaten supply chains, and increase the cost of goods nationwide. Other stakeholders, including the Clean Freight Coalition, American Trucking Associations, and Truckload Carriers Association, have voiced similar concerns regarding GHG3 and its reliance on currently unproven and costly zero-emission technologies.
However, Mullen noted that rescinding GHG Phase 3 could open doors for cleaner transportation by reallocating resources to enhance and promote alternative fuel sources for heavy trucks, which are crucial for the nation’s freight network.
Chris Spear, President and CEO of American Trucking Associations, characterized the GHG Phase 3 rule as “disastrous,” claiming that it would drive the trucking industry toward economic collapse, disrupt supply chains, and raise prices for American families. He reiterated the industry’s commitment to clean air while criticizing GHG3 for neglecting existing technologies that can effectively reduce emissions at lower costs. Spear emphasized that the trucking industry has consistently focused on reducing emissions over the past four decades and supports cleaner and more efficient technologies, provided they are grounded in practical realities.
Effect on Equipment
Considerable engineering work has already been done on diesel engines to comply with the 2027 emissions regulations facing scrutiny. Many aftertreatment systems have been entirely revamped, and electrical systems and engines have undergone redesigns, resulting in the creation of a new category of diesel engine oil aimed at compliance.
Several truck and engine manufacturers have indicated that they intend to release EPA ’27-compliant engines for the 2027 model year, regardless of federal requirements. Under the scrutiny of the EPA’s 2027 Low-NOx Rule, the useful life for regulated trucks has been increased from 435,000 miles to up to 650,000 miles, along with extended emissions systems warranties up to 450,000 miles for 2027 trucks. OEMs concurred that maintaining existing warranty levels rather than adjusting them under the new rule would help manage costs for new fleets.
The most likely scenario is that a pre-buy for the 2027 model year will be entirely off the table if Zeldin’s proposal proceeds. Ongoing challenging economics within the trucking sector, tariffs, and Trump’s previous repeals of California’s emissions waivers have already dampened expectations for a rush of sales ahead of the 2027 model year.
In June, President Trump enacted measures to dismantle California’s vehicle emissions standards by signing three Congressional Review Act resolutions, revoking the state’s waiver under the Clean Air Act. However, this action is facing legal challenges.
Additionally, the California Air Resources Board maintains that the Clean Truck Partnership (CTP), signed with major North American heavy truck OEMs in 2023, remains legally binding, holding truck and engine manufacturers to standards that were repealed by President Trump.
