In 2012, the California Air Resources Board (CARB) adopted the Advanced Clean Cars I (ACC I) regulations. These regulations include the LEV III regulation for criteria pollutants (LEV III Criteria), GHG (LEV III GHG) emissions, and the ZEV regulation and combine the control of smog-causing (criteria) pollutants and GHG emissions into a single coordinated package of regulations through the 2025 model year.

In 2022, the Board adopted the ACC II regulations, which establish the next phase of these regulations beginning with the 2026 model year. ACC II increases the stringency of criteria air pollutant emissions standards (LEV IV), updates the ZEV regulation to require 100% ZEV sales by the 2035 model year, and establishes a suite of assurance measures for ZEVs to ensure they can provide enduring emission reductions. CARB did not amend the LEV III GHG emission standards during the ACC II regulatory process.

CARB staff has now launched a new effort to consider potential amendments to the ACC II regulations, including updates to the tailpipe greenhouse gas emission standard and limited revisions to the Low-emission Vehicle and Zero-emission Vehicle regulations.

Left alone, the GHG emission standards level out in stringency after the 2025 model year and remain in effect for subsequent model years. Staff are evaluating regulatory concepts to support the State’s climate goals that the appropriate stringency and flexibilities of the emission standards and areas where coordination or alignment with federal standards would be beneficial.

For criteria air pollutants, staff are monitoring federal proposals for both light- and medium-duty emission standards and will consider potential amendments as appropriate after federal proposals are finalized.

For ZEVs, staff are considering new proposals to address emerging ZEV-related issues, such as requirements to help improve interoperability between electric vehicles and charging equipment and data collection to inform a consumer-facing window sticker. Staff are also considering processes to support implementation of the ACC II ZEV regulation, including certain environmental justice provisions.

On 15 November, CARB is holding a public workshop in Riverside, California, to provide information about the potential updates to the Advanced Clean Cars (ACC) regulations. Staff will discuss and seek input on several topics including: concepts for regulatory updates to CARB’s low-emission vehicle (LEV) greenhouse gas (GHG) emission standards for model years beyond 2025; coordination between California’s LEV IV and the proposed federal Tier 4 program for light- and medium-duty vehicle criteria air pollutant requirements; and emerging topics and implementation updates related to CARB’s zero-emission vehicle (ZEV) regulation. Staff will also cover next steps and a potential rulemaking timeline.