The Advanced Clean Cars II regulations are a package of California rules requiring automakers to sell a rising share of zero-emission vehicles each model year, reaching 100% by 2035, while also tightening tailpipe pollution limits on the gas-powered cars still on sale during the transition. The rules technically remain on the books, but their enforcement is currently suspended: on June 12, 2025, President Trump signed three Congressional Review Act resolutions revoking the EPA waiver that gave California authority to enforce ACC II. Litigation over that revocation is pending, so the practical status of the program in 2026 depends on what the courts decide.
Why the Rules Aren’t Currently Being Enforced
California can only set vehicle emission standards stricter than federal rules if the EPA grants a waiver under Section 209 of the Clean Air Act.1US EPA. Vehicle Emissions California Waivers and Authorizations The EPA granted a waiver for ACC II, but the June 2025 resolutions revoked it, along with waivers for the Advanced Clean Trucks and Low NOx rules.
Without that waiver, California and the states that adopted its standards under Section 177 of the Clean Air Act lost their legal authority to enforce ACC II.2Office of the Law Revision Counsel. 42 U.S. Code 7507 – New Motor Vehicle Emission Standards in Nonattainment Areas California and a coalition of states filed suit in the Northern District of California, and a separate challenge to the original waiver grant is before the Ninth Circuit.3California Air Resources Board. Current Litigation A motion hearing was scheduled for late January 2026.
The immediate effect is a freeze. Automakers built their product plans around ACC II, and most are continuing to produce electric vehicles to meet market demand and hedge against a court reversal, but the sales percentages below cannot currently be enforced against a manufacturer that misses them. If the courts restore the waiver, the mandates snap back. If the revocation stands, the ZEV quotas become unenforceable in every state that adopted them.
The Zero-Emission Vehicle Sales Schedule
ACC II sets a year-by-year ramp for the share of new passenger cars and light-duty trucks each manufacturer must deliver as zero-emission vehicles, running from model year 2026 through 2035:4California Air Resources Board. 13 California Code of Regulations 1962.4 – Zero-Emission Vehicle Standards for 2026 and Subsequent Model Year Passenger Cars and Light-Duty Trucks
- 2026: 35%
- 2027: 43%
- 2028: 51%
- 2029: 59%
- 2030: 68%
- 2031: 76%
- 2032: 82%
- 2033: 88%
- 2034: 94%
- 2035 and beyond: 100%
Battery-electric vehicles and hydrogen fuel-cell vehicles both count toward the percentage. A manufacturer that beats the target in a given year banks surplus credits for future use or sale to another automaker; one that falls short has three model years to close the deficit.
How Plug-In Hybrids Count
Plug-in hybrids can fill part of a manufacturer’s ZEV obligation, but not all of it. PHEVs are capped at 20% of the annual ZEV requirement in any model year, which keeps most of the mandate pointed at fully electric drivetrains.5California Air Resources Board. California Moves to Accelerate to 100% New Zero-Emission Vehicle Sales by 2035
To qualify at all, a PHEV must deliver at least 50 miles of all-electric range under real-world driving. The certification standard is higher: 70 miles of all-electric range on the standard test cycle and 40 miles on the more aggressive US06 highway cycle. The gas engine also has to meet the strictest tailpipe emission tier so the vehicle stays clean when the combustion engine runs.
Battery Warranty and Health Disclosure
ACC II sets a minimum battery warranty that follows the vehicle even after resale. For model years 2026 through 2030, manufacturers must warrant that the battery keeps at least 70% of its original capacity for 8 years or 100,000 miles, whichever comes first. Starting with model year 2031, the retained-capacity floor rises to 75% over the same 8-year or 100,000-mile period.6Legal Information Institute. California Code of Regulations Tit. 13, 1962.8 – Warranty Requirements for Zero-Emission Vehicle Standards
Manufacturers must also make battery state-of-health data visible so used-EV buyers can see how much capacity remains before they buy. Independent repair shops get access to the same diagnostic and battery information as dealer technicians, which keeps third-party service viable.7California Air Resources Board. Public Hearing to Consider Advanced Clean Cars II Regulations Final Statement of Reasons for Rulemaking
Tighter Limits on the Gas Cars Still Being Sold
The Low-Emission Vehicle IV portion of ACC II applies to the internal-combustion vehicles that will continue to be sold as the ZEV share ramps up. It tightens the fleet-wide averages for non-methane organic gases and nitrogen oxides, the main smog-forming pollutants.
The particulate matter standard is the sharpest change. Beginning with model year 2026, at least 50% of a manufacturer’s light-duty fleet must meet a 1 milligram-per-mile particulate limit over the vehicle’s full useful life, with the rest allowed up to 3 milligrams per mile. By model year 2028, 100% of gas-powered vehicles must hit the 1 milligram standard.8California Air Resources Board. 13 California Code of Regulations 1961.4 – Exhaust Emission Standards and Test Procedures for 2026 and Subsequent Model Years Evaporative emission limits are also tightened, and the highest-emitting vehicle certification categories are eliminated.
States That Adopted ACC II
Section 177 of the Clean Air Act lets any state adopt California’s standards in place of federal ones, provided the rules are identical to California’s and adopted at least two model years before they take effect.2Office of the Law Revision Counsel. 42 U.S. Code 7507 – New Motor Vehicle Emission Standards in Nonattainment Areas Before the waiver revocation, more than a dozen states had formally adopted ACC II:
- Starting with model year 2026: California, Massachusetts, Oregon, Vermont, Virginia, and Washington.
- Starting with model year 2027: Colorado, Delaware, Maryland, New Jersey, New Mexico, New York, and Rhode Island.
States entering in 2027 pick up the schedule at that year’s 43% figure rather than restarting at 35%, because the percentages are tied to model year, not adoption date. All of these states rely on California’s waiver, so the June 2025 revocation suspends enforcement in every one of them, not just California. If the revocation is upheld, each state would have to decide whether to pursue clean-vehicle policies under its own authority or fall back to federal standards.
Credits, Trading, and Penalties
Every zero-emission vehicle sold generates credits based on powertrain type and range, tracked in a state credit bank. Manufacturers over the target can bank surplus credits for future model years or sell them to competitors. A deficit from one model year must be closed within three. A shortfall in the 2027 model year, for example, must be resolved by the end of the 2030 model year.
The civil penalty for a ZEV credit shortfall is capped by California statute at $5,000 per credit.9California State Legislature. AB 1685 Assembly Bill – Chaptered Selling a vehicle that fails to meet emission standards can draw civil penalties of up to $37,500 per vehicle. Whether either penalty can be assessed depends on the outcome of the waiver litigation.
What About Federal EV Tax Credits
The federal purchase incentives that many buyers ask about are gone. The Inflation Reduction Act’s clean vehicle credits, worth up to $7,500 for a new EV and up to $4,000 for a used one, were terminated for vehicles acquired after September 30, 2025, under the One Big Beautiful Bill Act (Public Law 119-21), signed on July 4, 2025.10Internal Revenue Service. Credits for New Clean Vehicles Purchased in 2023 or After
With no federal purchase credit in place for 2026, the after-tax cost of an EV depends on state and local programs, which vary widely among the ACC II states. Most states also charge an annual registration surcharge on electric vehicles to offset lost gas-tax revenue, ranging from roughly $50 to nearly $300.