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Know the Global Warming Score

If you are looking to reduce your carbon footprint and save money, then buying a car with a higher Global Warming Score is a sure way.

In California all vehicles manufactured after January 1, 2009 were required to display a Global Warming Score and Smog Score as part of the California Environmental Performance (EP) Label. The Global Warming Score ranks each vehicle�~@~Ys CO2-equivalent value on a scale of 1-10 (10 being the cleanest) relative to all other vehicles. Vehicles with higher Global Warming Scores tend to burn less fuel, saving you money and reducing your carbon footprint.

New Fuel Economy and Environment Label Coming in 2013

In 2012 California harmonized its consumer vehicle labeling program with the Federal program so that starting in 2013, all new cars are required to display the new Fuel Economy and Environment Label (Label). The Federal label has a similar ranking system as well as additional ways to compare vehicles, such as:

  • New ways to compare energy use and cost between new-technology cars that use electricity and conventional cars that are gasoline-powered.
  • Useful estimates on how much consumers will save or spend on fuel over the next five years compared to the average new vehicle.
  • Easy-to-read ratings of how a model compares to all others for smog emissions and emissions of pollution that contribute to climate change.
  • An estimate of how much fuel or electricity it takes to drive 100 miles.
  • Information on the driving range and charging time of a plug-in vehicle.
  • A QR Code that will allow users of smartphones to access online information about how various models compare on fuel economy and other environmental and energy factors.

Until the transition to the new Federal ratings in mid-2013, the Environmental Scores displayed on the DriveClean web site remain based on the California EP Label scoring system.

Global Warming

Greenhouse gases (ghg) trap heat in the atmosphere, thereby creating a greenhouse effect known as global warming. Some greenhouse gases occur naturally and are emitted in the atmosphere through natural processes and human activities. Other greenhouse gases are created only through human activities. Scientists are certain that human activities are changing the composition of the atmosphere and that increasing the concentration of greenhouse gases will eventually change the planet's climate.

Greenhouse Gases

Greenhouse gases (ghg) emitted from vehicles include Carbon Dioxide (CO2), Methane (CH4), Nitrous Oxide (NO2), and Hydroflurocarbons (HFCs) from air conditioner refrigerant. The sum of all these greenhouse gas emissions are identified as the CO2-equivalent value, which is used to determine a vehicle�~@~Ys Global Warming Score.

How the Global Warming Score is Determined

The global warming score is based on emissions data from ARB�~@~Ys motor vehicle greenhouse gas emissions regulation known as AB 1493 or Pavely. The greenhouse gas regulation establishes a CO2-equivalent value that includes all the various global warming gases based on their relative contribution to global warming. The Environmental Scores displayed on the DriveClean web site are currently based on the California EP Label scoring system and will be transitioned to the new Federal ratings in mid-2013.

The CO2-equivalent value is as follows:

CO2 Equivalent = CO2+296xN2O+23xCH4�~@~SA/C Direct Emissions Allowance�~@~SA/C Indirect
Emissions Allowance

Using this equation, and accounting for the upstream emissions factor for alternative fuels, ARB accounts for all global warming gasses being released into the atmosphere due to the operation of each vehicle.

The upstream emissions, emissions from processes up to when the fuel enters a vehicle �~@~S typically during extraction, production, distribution, and dispensing of the fuel are taken into consideration when determining the Global Warming Score. These upstream emission factors are:

Upstream Adjustment Factors for Alternative Fuels

Fuel CO2Equivalent
Adjustment Factor
Conventional Gasoline (RFG)
Compressed Natural Gas (CNG)
Liquid Propane Gas (LPG)
Ethanol (E85)

Upstream CO2-equivalent Values for Hydrogen Internal Combustion Engine, Hydrogen Fuel Cell Electric, and Battery Electric Vehicles

CO2EquivalenT Value
Hydrogen �~@~S Fuel Cel
Hydrogen �~@~S Internal Combustion Engine (ICE)

Scale for the Global Warming Score

The table below shows the CO2-equivalent emission levels for each Global Warming Score. The average vehicle available in California today will get a Global Warming Score of 5. The Environmental Scores displayed on the DriveClean web site are currently based on the California EP Label scoring system and will be transitioned to the new Federal ratings in mid-2013.

Global Warming Score CO2 �~@~S equivalent Grams per mile
10 Less than 200
9 200-239
8 240-279
7 280-319
6 320-359
5 360-399
4 400-439
3 440-479
2 480-519
1 520 and up


Additional Resources

Find Clean Vehicles

Slide arrows to view vehicles by score. Scores of seven or higher are the cleanest.

Global Warming Score

Smog Score

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