States Adopting CARB Emission Standards

You probably know that California tends to love its regulations—especially when it comes to cars. And since what starts in California usually ends up parked in your garage, it’s important for you to know a few things about California’s emission standards, established by the California Air Resources Board (CARB).

It boils down to emissions rules, fuel economy targets, and zero-emission mandates—and it’s important because even though California’s right there in the name, other states can (and do) choose to follow that same rulebook instead of federal standards.

So whether you’re in the business of vehicle conversions, fleet management, or just thinking about future-proofing your ride, this knowledge matters. A lot. Let’s get into it.

California Emission Standards: Who Are the CARB States?

CARB stands for California Air Resources Board—the folks behind the state’s famously strict emissions policies. And thanks to Section 177 of the Clean Air Act, other states can adopt California’s standards, too.

As of 2025, 17 states plus D.C. have done exactly that. These “CARB states” have either fully or partially adopted California’s vehicle regulations:

Current CARB states include:

1. New York

2. New Jersey

3. Massachusetts

4. Oregon

5. Washington

6. Colorado

7. Virginia

8. Maryland

9. Connecticut

10. Rhode Island

11. Maine

12. Vermont

13. Delaware

14. Minnesota

15. Nevada

16. New Mexico

17. Pennsylvania

18. Washington D.C.

And the list isn’t shrinking. More states are watching closely—especially as federal emissions rules tighten under the EPA’s updated guidelines.

Key Differences Between Federal and California Emission Rules

You might be wondering why states would choose California’s rules over the federal standards—especially because California’s rules are generally tougher.

Well, that’s actually exactly why states are adopting CARB.

While federal guidelines set broad baseline emissions standards and fuel efficiency targets nationwide, California has special permission under the Clean Air Act to set more stringent policies, especially concerning zero-emission vehicles (ZEVs), meaning CARB states are typically progressively leaning.

Practically speaking, this means that California (and other CARB states) typically enforce stricter emissions limits for gas-powered vehicles, establish more aggressive fuel efficiency and emissions-reduction targets, and mandate higher quotas for electric and zero-emission vehicle sales. So, if you’re building, selling, or even just owning cars in these states, California’s rules mean you’ll probably need to clear higher regulatory bars than the ones set at the federal level.

States Adopting California Vehicle Regulations

If you live or operate in a CARB state, you’re likely facing stricter emissions compliance than your neighbors across the border. That means tighter emissions testing and lower allowable ceilings on gas-powered vehicles.

Additionally, manufacturers are expected to meet higher zero-emission vehicle (ZEV) sales quotas. Many of these states are also pushing earlier timelines for phasing out new internal combustion engines entirely; California, for example, is targeting 2035, and several other CARB states are following suit.

This is about preparation. Whether you’re managing a fleet or just a fan of classic cars, state-level regulation is going to impact how, what, and where you build and drive. California alone accounts for over 10% of all U.S. vehicles. So when they set the bar, everyone else eventually starts doing chin-ups.

What This Means for Converters, Fleets, and Builders

At first glance, CARB regulations might feel like just another hurdle—but for the EV conversion world, they’re actually a major opportunity. As more states adopt California’s stricter emissions standards, demand for compliant, zero-emission solutions is only going up. And here’s why that’s a good thing: converting an existing gas vehicle to electric is often the most cost-effective, regulation-friendly way to meet those standards—especially for fleets and municipalities with aging assets. CARB rules are pushing more people to look beyond new EV purchases and toward conversion as a smart alternative. If you’re already in the conversion game, that means more projects, more incentive-backed retrofits, and a growing market that’s being shaped by regulation—for the better.

Incentives for Clean Trucks and Buses

The Hybrid and Zero-Emission Truck and Bus Voucher Incentive Project (HVIP) is a California initiative that offers point-of-sale discounts to promote the adoption of clean, advanced commercial vehicles. Launched by the California Air Resources Board in 2009, HVIP aims to accelerate the deployment of zero-emission and near-zero-emission trucks and buses by reducing their upfront costs. The program provides vouchers to eligible public and private fleet operators, with larger incentives available for vehicles operating in disadvantaged communities. By facilitating the transition to cleaner transportation options, HVIP supports California's goals to reduce greenhouse gas emissions and improve air quality across the state .

Final Thoughts: CARB Isn’t Just a California Thing

Whether you’re in Oregon or Ohio, the writing’s on the wall: emission regulations are going local, and they’re getting stricter. California just happens to be leading the charge—and many other states are catching up.

So if you’re thinking about converting your fleet, upgrading your compliance, or selling vehicles across state lines, this matters.

Don’t wait for mandates to sneak up on you. Stay ahead of regulation, plug into the shift, and build with confidence—no matter what state you’re in.