All you need to know about California’s Advanced Clean Fleets regulation

Jonathan Norris

February 8, 2024
April 28, 2023

Today, on April 28th, the California Air Resources Board (CARB) adopted the Advanced Clean Fleets (ACF) regulation, which will require many fleets to deploy medium- and heavy-duty (MHD) zero emission vehicles (ZEVs) as early as 2024. Read on to learn more about the ACF, whether your fleet will be affected, key deadlines, and steps you can take to ensure a successful transition to ZEVs.

What is the ACF regulation?

CARB has long promoted zero emission vehicles as critical to reducing emissions and protecting the environment.  The ACF rule is CARB’s most ambitious zero emissions regulation yet; fleets will be required to deploy ZEVs such that they make up an increasing percentage of the total number of vehicles in the fleet. For example, for a fleet of package delivery vehicles, 10% of those vehicles must be ZEVs by 2025, 25% by 2028, 50% by 2031, 75% by 2033, and 100% by 2035. CARB provides a useful summary of the regulation on its web page.

Does the ACF rule apply to my fleet?

The ACF regulation applies to the following types of fleets:

  • Drayage fleets
  • State, local, and federal government agency fleets
  • “High priority fleets,” defined by CARB as fleets that...
  1. Have $50 million or more in gross annual revenues, or
  2. Own, operate, or have common ownership or control of a total of 50 or more vehicles (excluding light-duty package delivery vehicles)

Note that the ACF only applies to fleets that operate in California, though other states may follow suit by passing similar legislation.

Also, the ACF regulation applies to the following vehicles types:

  • MHD on-road vehicles with a gross vehicle weight rating (GVWR) greater than 8,500 pounds
  • Off-road yard tractors
  • Light-duty mail and package delivery vehicles

What is the schedule for fleets to transition to ZEVs?

The required timeline for transition varies depending on fleet type and vehicle type. 

Requirements for drayage fleets

By January 1st, 2024, all drayage trucks must be registered in CARB’s Online System in order to do business in California. From that day on, only ZE drayage trucks will be allowed to register in the CARB Online System. Internal combustion engine (ICE) drayage trucks registered through December 31, 2023 will be allowed to operate through their minimum useful life.

All drayage trucks entering seaports and intermodal railyards will be required to be ZE by 2035.

Source: California Air Resources Board

Requirements for fleets owned by state and local agencies

State and local agency fleets have a couple compliance options, depending on fleet size. Fleets with more than 10 vehicles will be required to make 50 percent of their vehicle purchases ZE beginning in 2024 and 100 percent by 2027. Small fleets with 10 vehicles or less will be required to start ZEV purchases beginning in 2027. State and local government fleets are permitted to purchase either ZEVs or near-ZEVs, or a combination of both, until 2035. Starting in 2035, only ZEV purchases will be allowed.

Instead of following this timeline, state and local government fleets can choose to follow the ZEV Milestones Option timeline shown below.

Requirements for high priority and federal fleets

High priority and federal government fleets must begin purchasing ZEVs beginning in 2024. Starting January 1st, 2025, these fleets must remove their ICE vehicles at the end of their useful life.

Like state and local government fleets, high priority and federal government fleets can instead elect to follow the ZEV Milestones Option timeline shown below.

Another timeline option for high priority and government fleets

High priority and government fleets can choose to follow the ZEV Milestones Option, shown in the table below.

Percentage of vehicles that must be ZE 10% 25% 50% 75% 100%
Box trucks, vans, buses with two axles, yard tractors, light-duty package delivery vehicles 2025 2028 2031 2033 2035 and beyond
Work trucks, day cab tractors, buses with three axles 2027 2030 2033 2036 2039 and beyond
Sleeper cab tractors and specialty vehicles 2030 2033 2036 2039 2042 and beyond

What steps should fleets take next?

Draft a fleet transition plan if you haven’t already done so

Planning is essential, since transitioning an entire fleet to ZEVs can require a significant investment of capital and resources. Major things to consider include EV procurement, charger selection and installation, site and equipment upgrades, funding and financing, and operating system adjustment needs. Our tool, Assess, can help you get started. It’s a free and publicly available platform to compare hundreds of EVs with comparable ICE vehicles on total cost of ownership, emissions, and infrastructure.

Get in touch with your utility as soon as you can

Deploying EVs means you will likely need to install charging infrastructure, and you will need to work with your electric utility to do this. Depending on the size and scale of your charging power needs, it could take anywhere from a few months to multiple years to get your site ready and commission the chargers, and utility equipment upgrades may be required. 

Get in touch with your utility as soon as you can to start the process, especially since utilities can often provide financial and technical support for installing charging infrastructure, ranging from rates designed to reduce electricity costs to charging infrastructure development and funding programs.

Prepare to operate EVs and chargers at scale

From working closely with several EV fleets, we know that successfully operating EVs can be difficult; challenges range from figuring out charging to managing new range limitations. You will likely need to make some adjustments to keep costs low and driving efficiency high. We’re here to help. Flipturn Connect is a unified platform that provides cross-system visibility into your fleet EV and charger operations. Connect helps fleets:

  • Manage their EVs, chargers, and other fleet systems, all in a single dashboard
  • Improve driving efficiency by tracking and analyzing energy consumption, regenerative braking, and other key metrics
  • Increase vehicle utilization by providing vehicle range and route energy insights
  • Save thousands on utility bills by scheduling charging to minimize demand charges and avoid peak rates.

Click here to read more about Flipturn Connect, and get in touch with us at