Understanding California’s Advanced Clean Cars II Regulation

This guide explains the Advanced Clean Cars II (ACC II) regulation in California, which aims to reduce light-duty vehicle emissions by 50 percent by 2040. The regulation mandates that original equipment manufacturers (OEMs) increase the sale of zero-emission vehicles (ZEVs) and plug-in hybrid electric vehicles (PHEVs), culminating in a requirement that 100 percent of sales be ZEVs or PHEVs by 2035.

• The ACC II regulation consists of two primary programs: the Zero-Emission Vehicle (ZEV) program and the Low-Emission Vehicle (LEV) program. The ZEV program requires that battery-electric vehicles (BEVs) and fuel-cell-electric vehicles (FCEVs) constitute an increasing share of annual sales, with specific requirements for battery size, charging compatibility (Level 1 and Level 2), range, and warranty. The LEV program focuses on strengthening pollutant emissions standards for light- and medium-duty vehicles, specifically targeting non-methane organic gas, oxides of nitrogen, carbon monoxide, formaldehyde, and particulate matter starting in model year 2025.
• ACC II introduces a 'vehicle value' accounting system for the period between 2026 and 2035, replacing the credit-based system used in the original ACC rule (2012-2025). Under ACC II, a ZEV sale equals one vehicle value, while a PHEV sale earns a partial value (between 0.63 and 1) based on range. PHEVs must have a minimum range of 43 miles through 2028, increasing to 70 miles thereafter, and are capped at 20 percent of an OEM's annual value requirements. By 2035, 100 percent of sales must be ZEVs or PHEVs.
• Compliance is mandatory for OEMs selling more than 4,500 light- and medium-duty vehicles per year; those selling fewer are exempt until 2035. OEMs can meet their targets through ZEV and PHEV sales, environmental justice (EJ) credits (capped at 5 percent of annual values), and flexibility measures such as trading, banking, pooling, and rolling over values. EJ credits are awarded for measures like providing minimum warranty and durability requirements, facilitating charging, and participating in community mobility programs.
• The regulation is projected to reduce light-duty vehicle emissions in California by 50 percent by 2040. According to the American Lung Association, a zero-emissions transportation sector from 2020 to 2050 could prevent 110,000 premature deaths, 2.78 million asthma attacks, and 13.4 million lost workdays.

APA

RMI (2023). Understanding California’s Advanced Clean Cars II Regulation. https://rmi.org/resources/understanding-californias-advanced-clean-cars-ii-regulation/

Chicago

RMI. Understanding California’s Advanced Clean Cars II Regulation. 2023. https://rmi.org/resources/understanding-californias-advanced-clean-cars-ii-regulation/.

Wikipedia

{{cite report |author=RMI |title=Understanding California’s Advanced Clean Cars II Regulation |date=13 June 2023 |url=https://rmi.org/resources/understanding-californias-advanced-clean-cars-ii-regulation/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{rmi2023understanding, author = {{RMI}}, title = {{Understanding California’s Advanced Clean Cars II Regulation}}, institution = {RMI}, year = {2023}, month = jun, url = {https://rmi.org/resources/understanding-californias-advanced-clean-cars-ii-regulation/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }