The Advanced Clean Fleets (ACF) Regulation complements the California Air Resources Board’s (CARB’s) Advanced Clean Trucks regulation to speed up the adoption of zero-emission technologies into the state’s truck and bus fleets that are well-suited for electrification. The rules mandate that targeted fleets lower emissions by phasing in the use of zero-emission vehicles (ZEVs) and that manufacturers only make ZEV trucks beginning with model year (MY) 2026.

It’s important to note that on January 13, 2025, California withdrew the state’s request for a Clean Air Act waiver for the ACF Regulation. CARB is considering its next actions. The agency isn’t enforcing the parts of the ACF rule that need federal permission, like the sections that apply to high-priority and drayage fleets. Not all parts of the ACF rule need this federal permission. ACF section for state and local government fleets is still in effect.

Requirements for state and local government fleets

The rule applies to agencies with authority in California that own, lease, or operate one or more vehicles in California that weigh more than 8,500 pounds. It can be a state or local government agency, including a city, county, public utility, special district, local agency or district, or a public agency of the State of California. It also applies to any department, division, public corporation, or public agency of the State of California.

Compliance requirements for state and local government fleets

Starting on January 1, 2024, half of a fleet’s annual vehicle purchases must be ZEVs. Beginning on January 1, 2027, all vehicle purchases should be ZEVs. Different parts of the same state or local government agency can meet these requirements together instead of separately.

Vehicles that are nearly zero-emission and have the MY 2035 or earlier are counted the same as ZEVs for this requirement. Any new vehicles with internal combustion engines (ICE), MY 2024 or newer, added to the California fleet after 2023 must meet California emissions standards. Any used ICE vehicle added must have an engine MY between 2010 and 2023.

State and local governments can choose to use the ZEV Milestones Option (available until January 1, 2030), which allows them to gradually introduce ZEVs into their fleets based on the suitability of different vehicles. If a fleet owner decides to use this option, they must report it. Once they choose this option, they can't switch back to the state or local government fleet requirements.

If a government fleet is small (with 10 or fewer vehicles) or operates in certain low-population areas and they're following the ZEV Purchase Schedule, they can wait until January 1, 2027, to start buying only ZEVs. But even these fleets have to start following other rules beginning on January 1, 2024, like reporting.

Recordkeeping and reporting requirements for state and local governments

Fleet owners need to complete and submit an annual report about their California fleet every year by April 1 through April 1, 2045. The report is based on the fleet as it stands on the first day of the year.

If a group of agencies decides to work together, each one still has to submit individual reports. The group may consist of different departments, divisions, districts, subsidiaries, or agencies.

Fleet owners must maintain records of the information they report and any related documents for at least five years. They must provide an electronic or paper copy within 72 hours of a written or verbal audit request from CARB.