Ecology is legally required to adopt California’s low- and zero-emission vehicle standards.
These manufacturer regulations don’t impose purchasing requirements on individuals or businesses; apply to used or off-road vehicles; or prohibit anyone from continuing to operate a gas- or diesel-powered vehicle in Washington.
Regulating new on-road vehicles
Under the federal Clean Air Act, states can either follow national emissions standards or adopt California’s more stringent standards, but they can’t create their own.
In 2005, the Washington Legislature passed a law directing Ecology to adopt California’s low-emission vehicle standards. In 2020, the Legislature passed another law requiring us to adopt California’s zero-emission vehicle standards as well.
After California passes a new emissions standard, other states can then adopt the standard through rulemaking. Following passage, California requests a “waiver of preemption” from the U.S. Environmental Protection Agency (EPA). If the EPA approves and issues the waiver, then California and other states that have adopted the emissions standard can enforce it.
To date, we’ve adopted four low-emission vehicle and zero-emission vehicle standards through the following regulations:
Advanced Clean Cars
Advanced Clean Cars II
Heavy Duty Low-NOx Omnibus
Advanced Clean Trucks
Together, these emissions standards regulate all new on-road vehicles sold in Washington.
Washington’s LEV standards require that any internal combustion engine vehicle sold in our state emits less air pollution and fewer greenhouse gases. To comply, manufacturers must put their vehicles through California's emissions testing procedures.
Light-duty LEV standards were first adopted in Washington in 2005. Medium- and heavy-duty LEV standards were adopted in 2022 with the Heavy-Duty Low NOx Omnibus regulation.
ZEV standards require manufacturers to sell increasing percentages of new ZEVs in Washington or purchase credits generated by those who exceed sales requirements. ZEVs include battery electric vehicles and hydrogen fuel cell vehicles.
Certain plug-in hybrid electric vehicles may also count as ZEVs under Washington’s vehicle emissions standards, even though they aren't “true ZEVs.”
Plug-in hybrids can only make up a limited percentage of new vehicle sales and must meet all-electric range requirements that vary by the weight of the vehicle.
Light-duty ZEV standards were adopted through the Advanced Clean Cars rule in 2021 and the Advanced Clean Cars II rule in 2022. Medium- and heavy-duty ZEV standards were adopted through the Advanced Clean Trucks rule in 2021.
Frequently asked questions
Vehicles are classified as light-, medium- or heavy duty depending on their size and the maximum weight they are designed to carry.
Light-duty vehicles are typically passenger cars used for personal commuting. Medium- and heavy-duty vehicles are typically commercial vehicles, with the exception of some larger pick-up trucks.
Manufacturers submit their vehicles to the California Air Resources Board (CARB) to be certified to the low-emission vehicle standards. Once approved, CARB issues executive orders for each vehicle that are sent to all states that have adopted California’s low-emission vehicle standards. This ensures the vehicles sent to those states for sale are in compliance and can be registered.
This process applies to light-, medium- and heavy-duty vehicles.
To comply with the zero-emission vehicle standards laid out in Advanced Clean Cars and Advanced Clean Cars II, manufacturers must sell enough light-duty clean vehicles to meet the sales requirement for each model year or purchase credits from those who exceed the requirements to make up their shortfall.
The sales requirements for each model year are underpinned by a credit system. Each new clean vehicle sold receives a credit value that varies depending on whether it’s a true ZEV versus a plug-in hybrid and whether the manufacturer claims additional environmental justice credits. Additional environmental justice credits can be earned for selling discounted ZEVs and selling ZEVs to dealers offering financial assistance. Manufacturers must sell enough clean vehicles to meet the credit requirement for each model year, which pencils out to a certain percentage of their new vehicle sales.
Model year
ZEV sales requirement
2025*
8-10%
2026
35%
2027
43%
2028
51%
2029
59%
2030
68%
2031
76%
2032
82%
2033
88%
2034
94%
2035 and beyond
100%
Advanced Clean Cars* only applies to model year 2025. Under this regulation, each vehicle receives 1-4 credits, which equals 8-10% of new light-duty vehicle sales.
Under Advanced Clean Cars II, the credit system was simplified so that the credit requirement for each model year is roughly the same as the sales percentage requirement. Advanced Clean Cars II begins with model year 2026 and requires 35% of new light-duty vehicles sold in Washington to be ZEVs. The sales requirement rises 6-9% each year until we reach 100% in model year 2035.
When we reach the 100% sales requirement, new light-duty vehicles made in model year 2035 or later that don't meet Washington’s standards won’t be able to be sold, registered, licensed, or rented within the state, even if they meet federal standards. Manufacturers can continue to sell plug-in hybrids, as long as they don't exceed 20% of new vehicle sales.
Advanced Clean Trucks is a flexible policy that allows manufacturers to comply by selling increasing percentages of new medium- and heavy-duty ZEVs in Washington or purchasing credits generated by those who exceed sales requirements.
Advanced Clean Trucks sales requirements under vary by vehicle weight class:
Model year
Class 2b-3 (8,501-14,000 lbs.)
Class 4-8 (14,001 lbs. and up)
Class 7-8 tractors (26,001 lbs. and up)
2025
7%
11%
7%
2026
10%
13%
10%
2027
15%
20%
15%
2028
20%
30%
20%
2029
25%
40%
25%
2030
30%
50%
30%
2031
35%
55%
35%
2032
40%
60%
40%
2033
45%
65%
40%
2034
50%
70%
40%
2035 and beyond
55%
75%
40%
If a manufacturer exceeds the sales requirements for a particular model year, the credits they generate can be saved to comply in the future or sold to those who fall short of sales requirements. Ecology allowed manufacturers to start generating credits four years before Advanced Clean Trucks took effect in model year 2025. Fifty percent of a manufacturer’s requirements each year can also be met with credits generated by plug-in hybrid vehicles.
Manufacturers that miss the sales requirement for a particular model year have a full year to make it up. California is considering extending this grace period to three years.
Most light-duty ZEVs have a range between 150 and 400 miles. Many light-duty vehicles can reach 80% charge in just 30 minutes, depending on the type of charger.
When it comes to medium- and heavy-duty vehicles, driving range averages 150-300 miles. But some models, like Tesla’s Semi, can drive up to 500 miles. Nikola’s hydrogen fuel cell tractor is rated for up to 750 miles of range. Many of today’s trucking routes can be served by existing ZEV technology, especially shorter haul and regional routes or routes that don't require maximum payloads. And truck buyers can choose which routes make sense for ZEVs.
There are more and more zero-emission trucks coming to market each year, and promising technologies that increase payload and range are being developed. Clean vehicle regulations are expected to drive even more innovation in this technology.
All new internal combustion engine vehicles available for sale in Washington must meet LEV standards. This is the manufacturer’s responsibility.
If the new vehicle is purchased in Washington, it will meet LEV standards. This may not be the case for new combustion engine vehicles purchased out of state, unless that state has adopted the same LEV standards as Washington. However, new combustion engine vehicles that don't meet LEV standards can't be registered in Washington even if they are purchased out of state.
Under medium- and heavy-duty LEV standards, manufacturers are allowed to sell some new engines and vehicles that have been certified to older standards if they offset emissions in other ways. So smaller quantities of these “legacy” engines and vehicles will still be available for purchase and registration. We’ll provide further guidance on legacy sales and registrations before these standards take effect in 2026.
Current regulations only require manufacturers to sell more new ZEVs in Washington, and they don’t place purchasing requirements on dealers or fleet owners.
We've heard that some manufacturers are passing on their compliance obligation by imposing sales requirements on dealers. We don’t require or recommend this practice, and we’re working to educate the industry about the many compliance options available to them.
Instead of meeting ZEV sales requirements, manufacturers have the option to purchase credits from those who have exceeded the sales requirements. We've allowed manufacturers to generate credits for their ZEV sales since 2021 — about four years before ZEV standards started taking effect.
Credits can be saved indefinitely in case a manufacturer anticipates a shortfall in the future. Manufacturers that miss the sales requirement for a particular model year have a full year to make it up.
No, Advanced Clean Trucks isn't ramping up more quickly in Washington than it did in California. The ZEV requirements for each model year are the same in both states, as required by the federal Clean Air Act.
In California, Advanced Clean Trucks took effect with model year 2024, which had a 5-9% ZEV sales/credit requirement. In Washington, Advanced Clean Trucks took effect with model year 2025, which has a 7-11% ZEV sales/credit requirement, matching the 2025 requirement in California.
Unlike in California, manufacturers selling in Washington have been able to generate and bank credits since 2021 without having to use them for compliance until model year 2025.
The upfront cost of a ZEV is generally higher than comparable gas- or diesel-powered vehicles. However, in many cases, ZEVs have a lower total cost of ownership. Those that don’t are expected to reach parity in the early 2030s, with exact timing varying by vehicle type.
The main driver of these total cost of ownership savings is the fact that electricity is cheaper than gasoline or diesel, and Washington has one of the largest gaps between electricity rates and fuel prices. Additionally, ZEVs tend to have lower maintenance costs. They don’t require oil changes, transmission fluid, spark plugs, air filters, or many other consumables found in combustion vehicles. Their brake pads usually last much longer because the vehicles capture and reuse as much as one-fifth of the energy normally lost during braking through “regenerative braking.”
The financial benefits of owning ZEVs are expected to continue to grow as purchase prices come down and charging infrastructure costs decline.
Advanced Clean Trucks requirements were designed to be feasible even in the absence of public charging infrastructure; they were written with only depot charging in mind. However, Washington is committed to robust support of the trucking industry through the transition to clean vehicles.
Over $130 million in funding from the Climate Commitment Act is being provided to help truck owners cover the costs of electric medium- and heavy-duty vehicles, as well as charging infrastructure. Additional state support has been made available through the Clean Fuel Standard, state tax credits on commercial ZEVs and associated infrastructure, as well as Volkswagen Settlement grants, Clean Diesel grants, and the Zero-Emission School Bus grant program.
We’re leveraging federal funding, too. Recently, the federal government announced awards under the Charging and Fueling Infrastructure grant program for Washington, Oregon, and California to build an electric truck charging corridor along the entirety of I-5, and the state has secured over $55 million in state and federal funding to electrify drayage trucks operating in and around ports.
The federal government also provides tax credits on charging infrastructure and tax credits on commercial ZEVs valued at up to $40,000 per vehicle, in addition to funding available through other programs, like the EPA’s Clean School Bus program.
Advanced Clean Fleets is another regulation California has adopted to address medium- and heavy-duty vehicle emissions. The policy requires that certain fleets purchase only zero-emission vehicles and requires manufacturers to sell only zero-emission vehicles starting in model year 2036.
California submitted a request for waiver authorization for Advanced Clean Fleets to the Environmental Protection Agency (EPA) in November 2023. The EPA hasn’t issued a determination on this waiver yet.
We’re required to maintain consistency with California’s motor vehicle emission standards, and we're monitoring EPA’s waiver authorization progress.
