CARB Issues Final ACF Regulations
On July 30th, CARB published the final draft of the ACF regulations. The application and scope of the regulations has retained language from the most recent 15 day draft, stating the regulations apply to fleets “contracts for the operation of.” The inclusion of this language is very concerning and further detailed in our 2nd 15-day comment letter which you can find here.
This final draft has been submitted to the Office of Administrative Law (OAL) which will review and give final approval of the regulations within 30 days. The review is only to ensure that CARB has followed the California Administrative Procedure Act, such as the Final Statement of Reasons (FSOR) responding to public comment, not a substantive review of the regulations.
Highlights from the Final Regulation Language Include:
- The Milestone and Purchase schedules have been revised and contain timelines based on the type of vehicle.
- The “Fleet Resiliency Exception” is an option for vehicles that support emergency response, but requires at least five percent of your fleet to be ZEV, caps the number of internal combustion engine vehicles exempted for fleet resiliency at 25 percent of your fleet, and limits the total number of all exemptions to the total number of ZEV in your fleet (meaning you must purchase at least one ZEV for every exempted internal combustion engine vehicle in your fleet).
- Reporting requirements include annually providing CARB with any contract for services.
- Annually applying or reapplying for exemptions that have been granted. Exemptions are only valid for one year.
- The Hiring Entity requirements have been retained.
- The language around those who contract with state or local governments remains.
- The regulations also add definitions for waste fleets. It also acknowledges the use of Captive Biofuel Use.
The definitions of fleet and fleet owner include the ambiguous language, “contracts for the operation of.” In the Final Statement of Reasons (FSOR) CARB state that the only contracted vehicles the regulations would apply to are “dispatched” vehicles.
“Dispatch” means to provide direction or instruction for routing a specific vehicle, whether owned or under contract, to specified destinations for specific purposes, including delivering cargo, passengers, property or goods, or providing a service.
While this is at least an attempt to be clearer than the last 15-day comment period draft, it is still unclear how helpful this guidance will be. Contract documentation reporting requirements under the regulations still include copies of “any agreement contracting for services using vehicles.” This reporting language is overbroad and significantly more administratively burdensome for state and local governments.
On June 6th, the California Air Resources Board (CARB) closed comment period on a 15-Day Comment Period set of amendments to their Advanced Clean Fleets (ACF) regulations mandating that state and local governments transition medium-duty and heavy-duty vehicle fleets to zero-emission vehicles (ZEV).
Sample letter for 2nd round of public comment and instructions for submission.
Those amendments were intended by CARB to clarify that vehicles under contract with a state or local government are considered part of the fleet for compliance with the ACF regulations. These amendments still do not address CSDA’s call for exempting vehicles that support emergency response.
CSDA provided public comment urging CARB to provide greater flexibility and exclude vehicles that support emergency services, consistent with our coalitions’ request in the public comment period that ended April 17.
Shortly following the release of this draft for public comment CARB also issued a “guidance” to the ACF regulations.
According to the newly released CARB guidance materials, the proposed ACF amendments are designed to:
- Improve compliance flexibility for public fleets;
- Repeal the High Priority Fleets and Drayage portions to provide greater regulatory certainty for private fleets; and
- Clarify responsibilities related to vehicles under contract.
On its updated guidance webpage, CARB highlights the “Key Updates” in this second 15-Day Comment Period draft:
- Public agencies must report vehicles under contract in their fleets when determining compliance with the ACF regulation.
- Private fleets are not subject to the ACF State and local government regulations.
- The regulation applies to public services performed by a State and local government agency, including functions carried out through contractual arrangements.
You can view CARB’s summary of the proposed changes here.
Previous 15-Day Public Comment Period Changes and Information
On April 17th, the California Air Resource Board (CARB) closed its 15-day public comment period on its proposed amendments to Advanced Clean Fleets (ACF) regulations.
This followed the previous 45-day comment period, where CSDA and our partners requested amendments. We are reiterating our request that vehicles that support emergency response need to be categorically exempted.
CARB has until August 1, 2026 to finalize its Final Statement of Record (FSOR) and submit its final rulemaking package to the Office of Administrative Law (OAL) for its current rulemaking process. The timing of the FSOR depends in part on the volume and complexity of public comments submitted. CARB is required to summarize and respond to every unique, relevant comment received during both the 45-day and both 15-day periods.
Depending on the volume of public comments, CARB may take weeks or months to analyze feedback and prepare its FSOR. If CARB determines that comments necessitate further "substantial" changes, they may initiate additional 15-day comment periods.
Key Takeaways from the 1st 15-Day Comment Period:
- Allows fleet owners to switch between the purchase and milestone schedules if they are currently in compliance
- All discretionary exemptions expire in 2030
- Excluded vehicle list (snow-removal vehicles, historical vehicles, etc.) remains unchanged (the only vehicles that will never be required to be ZEV under the regulations)
- “Fleet Resiliency" Exemption
- Must have 5 percent of your fleet ZEV to qualify (Previously 25%)
- Exempted vehicles for “resiliency” cannot exceed the number of current ZEVs in the fleet
- Total fleet exemptions (of any kind combined) must not exceed 25 percent, minus ICE vehicles already in the fleet purchased under a CARB exemption
- Deleted Public Utility Vehicles
- Defined Specialty Vehicles as over 33,000 pounds that are stationary to perform their functions
- Adds language addressing “waste fleets” and “wastewater fleets”
- Adds provisions exempting vehicles using “captive biofuel”
Exemptions are Burdensome and Do Not Meet Communities' Needs
- Caps “resiliency” at 25 percent of fleets that are necessary to support emergency services
- The exemption process is disjointed with requirements scattered across a multitude of code sections
- All are left to the discretion of the CARB Executive Officer, who may use “good engineering judgment,” which is defined as "using commonly believed scientific and mathematical principles when making a decision that seeks to maximize public benefit and minimize public harm"
- Includes exemptions for vehicles being unavailable and infrastructure delays, but they are still far too burdensome
- All exemptions require annual application and re-approval from CARB
Emergency Response Vehicles Should Be Excluded from the ACF Mandate
Vehicles reasonably anticipated to respond to emergency situations, or that support those efforts, should be excluded from the regulations in the same manner as the current regulation excludes snow removal vehicles.
Some examples of vehicles called upon to preserve public health and safety beyond those currently exempted:
- Vehicles used for fire prevention/mitigation, public safety, search and rescue, medical response, and poacher prevention should be excluded.
- Vehicles that are essential to the delivery, repair, and maintenance of electricity, water, wastewater, stormwater, and flood protection should be excluded.
- Vehicles used to prevent and respond to the spread of disease and dangerous vector outbreaks should be excluded.
Please support our advocacy efforts on this topic.
Flexibility Requested for Emergency Support Vehicles in CARB 45-Day Comment Period
On September 25, 2025, CARB approved Resolution 25-6-8 related to proposed amendments to ACF, which, among other things, repealed or provided clarity to those provisions related to private fleets that may not be entirely enforceable today due to the changes in federal law and withdrawal of certain waivers. The Board approved the resolution and directed staff to pursue further amendments that will have a future 15-day comment period. The totality of these two comment periods includes:
- Defining “traditional utility-specialized vehicle”
- Extending AB 1594 flexibility, such as that tied to the daily usage exemption, to all state and local fleets.
- Extending the 50 percent purchase requirement to 2030 vs. the current date of 2027, where 100 percent of purchases would have had to be ZEV going forward, and allowing small fleets and those located in designated counties to continue to wait until 2030 before they need to purchase any ZEVs at all.
- Streamlining the process for exemptions generally, including reducing barriers to applying for the Mutual Aid exemption, which currently requires an agency to already have 25 percent of their fleet ZEV in order to apply for the exemption.
- Further discussion and potential amendments on issues such as certain Renewable Natural Gas vehicles, and animal control vehicles
In advance of the coming 15-day comment period in which CARB will consider further amendments to its Advanced Clean Fleets regulation, CSDA and other organizations representing thousands of local agencies providing water, sewer, flood protection, fire protect, fire prevention, and other essential services, are calling upon CARB to ensure our frontline workers have the tools they require to perform their dangerous jobs under any conditions.
New Poll Released: Voters Support More Flexibility in ZEV Regulation
A new survey from Probolsky Research shows a vast majority of California voters – Republicans and Democrats – support exempting a broader range of emergency vehicles from the California Air Resources Board’s (CARB) Advanced Clean Fleets (ACF) zero emissions vehicle (ZEV) regulation.
Fire trucks, ambulances, and police cars are currently exempt from the regulation, which requires a transition to ZEVs for all state and local government medium-duty and heavy-duty vehicle fleets. Voters were asked whether this exemption should extend to all additional support vehicles anticipated to respond in emergencies like wildfires, floods and earthquakes. An overwhelming 75 percent of voters said they would support this change.
Support is strong among all voters with more than 70 percent of Democratic, nonpartisan, and Republicans in agreement. Given the importance to voters, the California Special Districts Association (CSDA) is calling on CARB to enact these exemptions, which would help protect lives and property.
Additional Background on CARB Advanced Clean Fleets Regulation
The Zero Emission Vehicle (ZEV) marketplace and regulations saw dramatic changes in 2025 including those stemming from the successful passage of (Garcia) in 2023, the California Air Resources Board (CARB) withdrawing its request for a federal Clean Air Act waiver for the Advanced Clean Fleets (ACF) regulation, and three successful Congressional Review Act resolutions that terminated the State of California’s waivers for Advanced Clean Trucks, Advanced Clean Cars II, and Heavy-Duty Omnibus. Generally, the remaining enforceable ACF regulations mandate the transition to zero-emission vehicles (ZEV) for state and local fleets.
CARB’s proposed regulatory changes were approved following a 45-day comment period, to which CSDA and its partners submitted comments that the proposed regulations do not go far enough to provide relief to local agencies, given the numerous challenges that they face in the marketplace to meet the ambitious timelines of the current mandate, particularly regarding vehicles anticipated to respond to emergency situations.
At the September 25, 2025 where CSDA and its partners testified, CARB approved Resolution 25-6-8 related to proposed amendments to ACF, which among other things, repealed or provided clarity to those provisions related to private fleets that may not be entirely enforceable today due to the changes in federal law and withdrawal of certain waivers. The Board approved the resolution and directed staff to pursue further amendments that will have a future 15-day comment period. The totality of these two comment periods includes:
- Defining “traditional utility-specialized vehicle”
- Extending AB 1594 flexibility, such as those tied to the daily usage exemption, to all state and local fleets.
- Extending the 50 percent purchase requirement to 2030 vs. the current date of 2027, where 100 percent of purchases would have had to be ZEV going forward, and allowing small fleets and those located in designated counties to continue to wait until 2030 before they need to purchase any ZEVs at all.
- Streamlining the process for exemptions generally, including reducing barriers to applying for the Mutual Aid exemption, which currently requires an agency to already have 25 percent of their fleet ZEV in order to apply for the exemption.
- Further discussion and potential amendments on issues such as certain Renewable Natural Gas vehicles, and animal control vehicles
CARB’s proposed regulations follow the successful passage AB 1594 (Garcia) in 2023, which aimed to ensure that California’s ZEV regulations, such as the ACF rules, provide practical flexibility for public agency utilities. The measure dealt with issues such as certain utilities’ ability to replace specialized medium- and heavy-duty vehicles that have reached the end of their service life—regardless of model year—when those replacements are necessary to maintain reliable service or to respond quickly to major events like wildfires, severe storms, natural disasters, or other large-scale emergencies.
AB 1594 also requires CARB to update how it measures daily vehicle usage. Instead of relying on minimal-use data or excluding high-use days, utilities will be able to submit more representative fleet data that reflects real-world operations.