Green Vehicle Laws and Regulations in California

California leads the country in planet-protecting standards for drivers and their vehicles. The following green vehicle laws cover everything from emissions test requirements for fuel-efficient cars, hybrids, and more to alternative fuel tax rates, from idle reduction regulations and programs to zero emission vehicle parking and charging laws.

Not only does CA boast numerous laws aimed at enhancing the environment. California also entices driver to go green with a long list of eco-friendly driver incentives. Keep in mind these laws and incentives are subject to change. Therefore, periodically reference this page, your local California Department of Motor Vehicles (DMV),, and the California Air Resources Board (ARB).

Zero Emission Vehicle (ZEV) Parking Decals and Permissions

Your electric vehicle must display a Zero Emission Vehicle (ZEV) Parking Decal in order to legally park and recharge your EV in designated parking spaces

Your local DMV office cannot process ZEV decal applications. Instead you must mail your completed Application for Zero Emissions Vehicle (ZEV) Parking Decal (REG 4048) and fees to:

Department of Motor Vehicles
Special Processing Unit MS D238
PO Box 932345
Sacramento, CA 94232-3450

Place your decal on the driver's side rear window or back bumper.

If your vehicle does not display a ZEV decal, you may not stop, stand, or park it in a stall or space specifically used for plug-in EV charging. This includes blocking access to parking.

Required Certification for Alternative Fuel Vehicle Conversions

Before converting an emissions-controlled vehicle�from running originally on gasoline or diesel fuel�to run on alternative fuels such as natural gas, propane, or ethanol, manufacturers must have the retrofit systems evaluated and approved by the California Air Resources Board (ARB).

For certification requirements for plug-in hybrids and alternative fuels such as hydrogen and biofuels, call the Help Line at (800) 242-4450. For example, according to the Alternative Fuels Data Center, CA permits the conversion of hybrid electric vehicles (model-year 2000 and newer) that are either passenger cars, light-duty trucks, or medium-duty vehicles, to be capable of off-vehicle charging, as long as you can demonstrate compliance with certain requirements. Again, call the Help Line for specifics.

As the manufacturer, you must obtain the certification of an alternative fuel retrofit system by demonstrating to the ARB compliance with emission, warranty, and durability requirements. Keep in mind, California's requirements for aftermarket fuel converters are not the same as those of the Environmental Protection Agency (EPA).

Who Can Obtain Certification

California defines a manufacturer as a person who sells an alternative fuel retrofit system in California that he has manufactured or assembled. Therefore, this doesn't apply to individuals wanting to convert their own vehicles for personal use.

Certified Retrofit Systems

Check the list of certified retrofit systems by the following model-year:

Alternative Fuel Tax Rates

California taxes compressed natural gas (CNG), liquefied natural gas (LNG), liquefied petroleum gas (LPG or propane), ethanol, and methanol at the following rates:

  • CNG—$.07 per 100 cubic feet (standard pressure and temperature).
  • LNG—$.06 per gallon.
  • LPG/propane—$.06 per gallon.
  • Ethanol/methanol—1/2 of the current tax on gasoline and diesel (for fuel blends with up to 15% gasoline or diesel fuel).

However, if your vehicle runs on CNG, LNG, or LPG/propane, you may opt to pay an annual flat rate fuel tax (instead of the above rates) based on the unladen weight of your vehicle. This does not include interstate users.

  • Passenger cars and other vehicles weighing 4,000 pounds or less $36.
  • Vehicles weighing more than 4,000, but less than 8,001 pounds $72.
  • Vehicles weighing more than 8,000, but less than 12,001 pounds $120.
  • Vehicles weighing more than 12,001 pounds $168.

For full details, refer to CA Revenue and Taxation Code 8651-8651.8.

Idle Reduction Requirements and Programs

Heavy-Duty Vehicle Idling

California limits the idling of new and in-use diesel trucks equipped with sleeper berths with the following regulations:

New engine requirements�Heavy-duty diesel engines (model-year 2008 and newer) must either
  • Be equipped with a nonprogrammable engine shutdown system that automatically shuts down the engine after it idles for 5 minutes, or
  • Meet a stringent-oxides-of-nitrogen idling emission standard.

In-use truck requirements�Operators of trucks equipped with sleeper berths (either registered in California or out-of-state) must shut down their engines when idling for more than 5 minutes anywhere within California.

Emissions performance requirements�The following applies to diesel-fueled auxiliary power systems (APS) and fuel-fired heaters installed on trucks with engines 2007 and newer, as they are both technologies used in lieu of idling the truck's main engine.

  • Diesel-fueled auxiliary powers systems (APS) must control particulate matter (PM) emissions either by routing the APS exhaust through the truck's PM trap or by retrofitting the diesel APS with a verified level 3 PM control device able to reduce PM emissions by at least 85%.
  • Fuel-fired heaters must meet the Ultra Low Emission Vehicle requirements detailed in the Low-Emission Vehicle regulations.

California's heavy-duty idling regulations are extensive. Refer to ARB's Heavy-Duty Vehicle Idling Emission Reduction Program for full details.

Regulations Limiting Idling on School Grounds

The following restrictions apply to those who drive a school bus, school pupil activity bus, youth bus, or general public paratransit vehicle:

  • You must turn off your engine upon stopping at a school (or within 100 feet of a school).
  • You may not turn on your engine more than 30 seconds before beginning to leave a school or from within 100 feet of a school.
  • You may not cause or allow your vehicle to idle anywhere beyond 100 feet from a school for:
    • More than 5 consecutive minutes, or
    • A period (or periods) totally more than 5 minutes in any one hour.

The following restrictions apply to those who drive a transit bus or commercial motor vehicle:

  • You must turn off your engine upon stopping at a school.
  • You may not turn on your engine more than 30 seconds before beginning to leave a school.
  • You may not cause or allow your vehicle to idle anywhere within 100 feet of (but not at) a school for:
    • More than 5 consecutive minutes, or
    • A period (or periods) totally more than 5 minutes in any one hour.

Of course, there are exceptions to the above rules. Some of these exemptions include:

  • Being stuck in traffic conditions that are out of your control.
  • When necessary to idle your vehicle for testing, servicing, repairing, or diagnostic purposes.
  • While operating equipment needed for disabled passengers and climate control devices for children with exceptional needs.

Consult the amended regulation for a full list of exemptions and rules, and the School Bus Idling Airborne Toxic Control Measure for additional resources.

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