The California Air Resources Board has voted unanimously to finalize its Advanced Clean Fleets (ACF) rule, a massive new regulation on medium- and heavy-duty fleet vehicles that, among other things, requires all new medium- and heavy-duty vehicles sold or registered in the state of California to be zero-emission come 2036.

The rule is a complement to CARB’s previous Advanced Clean Trucks (ACT) rule adopted in 2020.

The two rules are similar but distinct. ACT was primarily a manufacturer requirement, requiring that manufacturers supply enough electric trucks. ACF will be a fleet adoption requirement, requiring that commercial fleet operators purchase a certain percentage of electric trucks.

In the interim few years, it has become apparent that not only are climate change and pollution becoming even more urgent, but that the market for EV trucks has advanced significantly, with hundreds of total models available, across every truck class from 2b through 8. And these trucks have more than enough range for most fleet applications, which often have predictable daily usage schedules.

Because of this, the ACF rule has been strengthened since it was first proposed. Despite originally starting as an urban delivery truck requirement, then morphing into a sales requirement for several types of fleets, it has now been modified to improve on ACT and require even more of manufacturers.

Among these requirements is a new 2036 target for an end to diesel truck sales. This was lowered from an early 2040 target, with the thought that 2040 would be too late to reach California Governor Gavin Newsom’s goal for 100% zero-emission medium- and heavy-duty vehicles by 2045. Nine years gives a lot more wiggle room than five years to turn over the entire state’s fleet, though nine years is still a tight timeline.

The rule does not affect existing equipment and has provisions to allow vehicles to continue being used throughout their typical full useful life.

California is particularly sensitive to air quality issues as it’s home to the two largest ports in the US and is situated in a natural geographic bowl that traps pollution.

The ACF rule is thought to be the strongest medium- and heavy-duty truck regulation in the world, and the first to ban the sale of diesel trucks.