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 are required to display a Global Warming Score and Smog Score as part of the Environmental Performance Label. The Global Warming Score is a score that ranks each vehicle’s 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.
When comparing Global Warming Scores on the dealership lot, remember that scores may vary even within the same vehicle model. This may be due to differences in the engine or transmission or whether or not a vehicle is equipped with air conditioning.
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’s Global Warming Score.
How the Global Warming Score is Determined
The global warming score is based on emissions data from ARB’s motor vehicle greenhouse gas emissions regulatio 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 CO2-equivalent value is as follows:
CO2 Equivalent = CO2+296xN2O+23xCH4–A/C Direct Emissions Allowance–A/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 – typically during extraction, production, distribution, dispensing of the fuel. of alternative fuels 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) |
1.00 |
Compressed Natural
Gas (CNG) |
1.03 |
Liquid Propane Gas
(LPG) |
0.89 |
Ethanol (E85) |
0.74 |
Upstream CO2-equivalent Values for Hydrogen Internal
Combustion Engine, Hydrogen Fuel Cell Electric, and Battery Electric
Vehicles
Fuel |
CO2EquivalenT Value (grams/mile) |
Electricity |
130 |
Hydrogen – Fuel Cel |
210 |
Hydrogen – Internal
Combustion Engine
(ICE) |
290 |
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.
| Global Warming Score | CO2 – 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 |