CARB to repeal Advanced Clean Fleets regulation
13 May 2025
Under a legal settlement reached on May 2nd between the State of Nebraska and the California Air Resources Boards (CARB), CARB agreed to repeal the Advanced Clean Fleets (ACF) regulation. The plaintiffs in the case—a group of 17 states led by Nebraska and the Nebraska Trucking Association—argued that, given California’s large population and access to international ports, the ACF rule would have had nationwide effects on the supply chains.
In the settlement, California agreed not to enforce the ACF requirements for High-Priority and Drayage Fleets, and to start the process to repeal the regulation. The ACF regulation specifies mandatory schedules to transition California heavy-duty vehicle fleets to zero-emission vehicles (ZEV)—such as battery electric trucks—beginning from 2024.
CARB has also agreed not to enforce the part of the ACF regulation requiring 100% zero-emission-vehicle sales in the medium- and heavy-duty categories beginning with model year 2036—unless CARB receives an EPA preemption waiver for that regulatory requirement.
Key ACF provisions were already not being enforced, as CARB withdrew its EPA waiver request for the regulation. However, it was not clear whether or not the 100% ZEV sales mandate from 2036 was enforceable without an EPA waiver.
It is still uncertain if any changes will be introduced to the ACF provisions pertaining to State and Local Government Fleets, which affect only fleets in the state and presumably do not require an EPA preemption waiver.
The withdrawal of the ACF rule could make it challenging to achieve the goals of the Advanced Clean Truck (ACT) regulation. The two regulations were designed to work together to advance the transition to heavy-duty ZEV fleets—the ACT rule imposes an obligation on manufacturers to supply ZEV vehicles in the state, while the ACF regulation would ensure adequate ZEV demand. With the ACF rule repealed, manufacturers may struggle to meet their sales targets for the more expensive and less functional electric trucks.
The ACT rule, which has received an EPA waiver but is now facing legal challenges, would require that 55% of new Class 2b-3 vehicles, 75% of new Class 4-8 vehicles, and 40% of new Class 7-8 tractors sold in California be ZEVs by 2035.
Source: Nebraska Attorney General