California is considering new regulations that would ban sales of new diesel semi trucks by the 2040 model year, accelerating the timeline for a shift to zero-emission trucks.

The requirement was laid out in a proposed rule released by the California Air Resources Board (CARB) August 30 and is scheduled for consideration by the regulator October 27.

The diesel ban would apply to all new medium-duty and heavy-duty commercial trucks sold in California beginning with the 2040 model year, with some exceptions for certain emergency vehicles.

 2019 Project Portal Truck--Kenworth/PACCAR

2019 Project Portal Truck--Kenworth/PACCAR

The rule would essentially take California's Advanced Clean Truck rules, which required commercial vehicle manufacturers to start selling EVs by 2024, to a new level. Those regulations were on the path to fully electric commercial trucks by 2045 but the proposed rule, part of the Advanced Clean Fleets regulation, lays out in detail how government and commercial fleets will make the shift.

In addition to laying out an end date for sales of new medium-duty and heavy-duty diesel trucks, the proposed rule also lays out timelines for different fleet operators to begin switching to zero-emission vehicles. In most cases, they would begin adding zero-emission vehicles before the end of the decade.

Volvo VNR Electric and Electrify America charging station

Volvo VNR Electric and Electrify America charging station

Manufacturers have begun moving toward electric trucks that will be needed to meet these requirements. Europe's largest truckmakers have committed to a phaseout of diesel sales by 2030.

The Megawatt Charging Standard is going to help enable this transition as well, but that will require much investment from truckmakers and state and federal governments.

On the passenger-vehicle side, California put its 2035 ban on engines in non-plug-in passenger vehicles into policy recently.