A new letter is pushing back on the Truck and Engine Manufacturers Association’s (EMA) recent criticism of California’s proposed amendments to the Advanced Clean Trucks (ACT) regulation. Addressed to leading truck and engine manufacturers — including Cummins, Daimler Truck North America, Ford, General Motors, Hino, Isuzu, Navistar, PACCAR, Stellantis, Volvo Group North America, and the EMA itself — the letter defends the amendments as both legally sound and vital for advancing zero-emission vehicle (ZEV) deployment, countering several claims made by EMA in its July 14 comments to the California Air Resources Board (CARB).
EMA argued that the proposed amendments, which would allow manufacturers to pool compliance credits across ACT opt-in states and increase flexibility in how ZEV credits are applied, are legally void following a Congressional Review Act (CRA) resolution passed earlier this summer. EMA contends that this resolution nullified EPA’s waiver of federal preemption, thereby eliminating state authority to enforce the ACT regulation outside of California.
The response letter, which was signed by groups such as the Electric Vehicle Association, the Natural Resources Defense Council and the Sierra Club, disputes that interpretation, asserting that California’s in-state ACT program remains in full effect and that states adopting similar rules still have a path forward, despite the CRA action. The letter further argues that credit pooling across opt-in states is a practical compliance tool and does not hinge on the waiver’s status.
“Regardless of EMA’s interpretation of the CRA resolution, the ACT rule continues to be valid in California, and states that have adopted the ACT rule through their own regulatory processes retain the authority to implement and enforce those standards,” the letter states.
EMA also took aim at the Clean Truck Partnership, a 2023 agreement between CARB and major truck manufacturers, claiming the proposed amendments were developed without sufficient consultation and therefore violate the partnership’s intent. The response letter rejects that argument, stating that while stakeholder engagement is important, it does not equate to giving manufacturers veto power over regulatory changes.
The EMA comments additionally cited poor ZEV adoption rates in California, noting that only 4% of Class 4-8 trucks registered in the state are zero-emission, far below the ACT’s 9% target. According to EMA, this shortfall reflects fundamental problems with the rule. However, the response letter characterizes such data as a temporary market lag and stresses the importance of sustained policy pressure to drive innovation and investment.
Despite EMA’s opposition, CARB formally adopted the ACT amendments at its July 24 hearing. The approved changes include credit pooling, expanded offset eligibility across vehicle classes, reduced electric range requirements for near-zero emission vehicles, and added compliance flexibility. CARB stated the amendments uphold the intent of the Clean Truck Partnership while preserving emissions benefits and reducing compliance barriers.
