Heavy Duty Trucking Logo
MenuMENU
SearchSEARCH

California Delays Advanced Clean Fleets Enforcement

Fleets that operate heavy-duty trucks in California will get a reprieve from enforcement of the state’s rules requiring zero-emission trucks that kick in starting Jan. 1.

Deborah Lockridge
Deborah LockridgeEditor and Associate Publisher
Read Deborah's Posts
December 29, 2023
California Delays Advanced Clean Fleets Enforcement

The California Air Resources Board is pushing for trucks in the state to be zero-emissions, battery-electric or fuel-cell electric.

Photo: CARB

3 min to read


Fleets that operate heavy-duty trucks in California will get a reprieve from enforcement of the state’s rules requiring zero-emission trucks that kick in starting Jan. 1.

The California Air Resources Board announced that it does not plan to enforce the drayage or high-priority fleet provisions of the Advanced Clean Fleets regulation until the U.S. Environmental Protection Agency grants a preemption waiver from the federal Clean Air Act or determines a waiver is not necessary.

Ad Loading...

However, this does not apply to state and local government fleets.

What is the Advanced Clean Fleets Regulation?

The Advanced Clean Fleets regulation was adopted by California Air Resources Board just last April and was effective Oct. 1.

The state’s goal is to have fleets operating in the state be 100% electric by 2035, 2040 or 2045, depending on size and type of truck. The regulation affects medium- and heavy-duty on-road vehicles with a gross vehicle weight rating greater than 8,500 pounds, as well as off-road yard tractors, and light-duty mail and package delivery vehicles, according to the CARB website.

Ad Loading...

However, many in the trucking industry have been concerned that zero-emission trucks might not be available in time, or the charging infrastructure.

Even some fleets that were committed to embracing ZEV trucks have been having trouble getting the trucks they ordered and the charging infrastructure installed.

HDT Truck Fleet Innovator Brad Bayne, VP of strategic initiatives for 4 Gen Logistics, had expected to have 64 battery-electric Class 8 trucks in its California drayage operations by September, having ordered 40 Volvo VNR Electric trucks and 20 Kenworth T680e electric trucks. Bayne told HDT Jan. 1 that the Volvos just now are starting to be delivered, and charging infrastructure remains a bottleneck.

"We have two [charging] sites built but can’t get them energized because we are waiting on utilities to do their part."

CTA's Lawsuit Challenging Advanced Clean Fleets Rules

In October, the California Trucking Association filed a federal lawsuit seeking to block enforcement of the rules.

Ad Loading...

The association contends that ACF conflicts with the Federal Clean Air Act and the Federal Aviation Administration Authorization Act of 1994.

“Congress has expressly preempted state and local rules that ‘relate to’ the control of emissions from new motor vehicles and state and local rules that ‘relate to’ a price, route, or service of any motor carrier,” CTA said.

“Because the ACF regulation is aimed at transforming not only the vehicles sold within California’s borders, but virtually any vehicle that enters those borders, CARB has disregarded what the United States Supreme Court has declared to be Congress’s carefully calibrated regulatory scheme,” the lawsuit said.

In November, CARB asked the EPA for a preemption waiver regarding the challenged provisions of the ACF rule.

According to published reports, the California Trucking Association agreed not to file a preliminary injunction motion seeking to enjoin enforcement of the challenged provision of the ACF regulation while the waiver request is pending before U.S. EPA.

Ad Loading...

More About CARB's ACF Enforcement Delay

In an enforcement notice issued Dec. 28, CARB encouraged fleets to go ahead and voluntarily report and comply with the regulations while the waiver request is pending. CARB said trucks powered by internal-combustion engines that are added to the reporting system after the original deadline may not be allowed to operate once the U.S. Environmental Protection Agency makes its decision on the waiver.

CARB will also accept requests for the extensions and exemptions available under the ACF regulation during this period.

However, CARB is keeping to the enforcement deadline for state and local government fleets, since it doesn’t need a federal Clean Air Act waiver for those fleets. So for state and local fleets, CARB will fully enforce all requirements, including reporting and the ZEV purchasing requirements or the option to comply with the ZEV Milestone Option, beginning Jan. 1, 2024.

Updated 1/2/2024 to add comment from Brad Bayne

More Fuel Smarts

Four men in suits on the National Mall with giant video screen showing capitol building in the background
Equipmentby Deborah LockridgeJuly 10, 2026

EPA Proposal Could Ease 2027 Truck Costs and Buying Uncertainty

The proposal doesn't change the tougher NOx standard, but it would revise key implementation requirements that manufacturers say have driven up costs and complicated fleet purchasing decisions.

Read More →
Illustration showing Paccar MX engine with sketch illustration of DEF fill tank in background
Equipmentby Deborah LockridgeJuly 7, 2026

Cummins, Paccar Ease DEF Derates After EPA Guidance

Updated diesel engine software gives truck operators more time to address emissions-system issues while staying compliant with EPA emissions standards.

Read More →
Illustration with wrenches in background with "Maintenance in the Messy Middle: Biodiesel" text and NACFE Run on Less logo
Maintenanceby Jack RobertsJuly 2, 2026

Maintenance in the Messy Middle Part 3: Biodiesel

Biodiesel can reduce emissions, improve fuel-system lubricity and use existing diesel infrastructure. But NACFE’s Messy Middle maintenance report says fleets must actively manage storage, cold-weather operation, filters and oil drain intervals to avoid problems.

Read More →
Ad Loading...
thermo king heavy duty trucking
SponsoredJuly 1, 2026

Enhance Fleet Performance with High-Efficiency Auxiliary Power Units

Drive sustainable cost savings while increasing driver comfort during short- and long-haul logistics operations.

Read More →
Illustration with wrenches in background with "Maintenance in the Messy Middle: Renewable Diesel" text and NACFE Run on Less logo
Maintenanceby Jack RobertsJune 29, 2026

Maintenance in the ‘Messy Middle’ Part 2: Renewable Diesel Fuel

NACFE's latest Messy Middle Powertrain Service & Maintenance report says renewable diesel gives fleets an opportunity to reduce carbon emissions without changing trucks, fueling infrastructure or maintenance practices. But technicians still need to understand several important operational differences.

Read More →
Illustration messy middle maintenance diesel with wrenches in background
Maintenanceby Jack RobertsJune 26, 2026

The Diesel Engine Enters NACFE’s ‘Messy Middle’

NACFE’s new Messy Middle Powertrain Service & Maintenance report says keeping modern diesel engines running now depends as much on software, diagnostics and data as traditional mechanical service.

Read More →
Ad Loading...
Illustration showing DEF tank and Detroit engine
Equipmentby Deborah LockridgeJune 18, 2026

DTNA Software Update Gives Truckers More Time Before DEF Derates Take Effect

The changes reflect EPA guidance aimed at reducing downtime caused by emissions-system faults while maintaining compliance requirements.

Read More →
Illustration of exhaust aftertreatment system on an AI-inspired blue background and a green fuel pump nozzle in the foreground.
Maintenanceby Deborah LockridgeJune 15, 2026

New Agentic Predictive Maintenance Report Demonstrates How Degraded Aftertreatment Systems Waste Fuel

Questar analyzed a large mixed-class fleet and discovered it was wasting as much as $30 in fuel per vehicle, per day, because of mechanically degraded aftertreatment systems.

Read More →
Amazon electric cargo bike on New York City street
Fleet ManagementJune 15, 2026

New York City's Microhub Project is Delivering Results

Trucking, last-mile delivery companies, and environmental advocates like what they are seeing so far with New York's microhub program.

Read More →
Ad Loading...
Red Kenworth truck pulling Paper Transport trailer
Fuel Smartsby Deborah LockridgeJune 2, 2026

Lessons Learned About Alternative Fuels: Start Small, Stay Flexible

Practical advice on adopting alternative fuels and ZEVs from HDT's 2026 Top Green Fleets, from renewable diesel and natural gas to electric trucks.

Read More →