Our "tons of greenhouse gases" rating gives you an estimate of each vehicle's impact on global warming. One of the most important things you can do to reduce global warming pollution is buy a vehicle with higher fuel economy.

Scientific evidence strongly suggests that the buildup of greenhouse gases in the atmosphere is raising the earth's temperature and changing the earth's climate - both have many potentially serious consequences. Transportation, specifically the combustion of fossil fuels in our vehicles, is the single largest source of human-made greenhouse gases. The more fuel your vehicle burns the more greenhouse gases it emits. Our estimates assume you drive a certain number of miles each year, but you can customize these assumptions to match your own driving patterns by selecting the customize option at the top of each vehicle page.

You may be surprised to know that most vehicles produce several times their weight in greenhouse gases each year. Not only does most of the fuel you put in your tank become greenhouse gas emissions, but the carbon in the fuel combines with oxygen in the air, almost tripling the weight of the fuel itself.

The greenhouse gas estimates presented here are "full fuel-cycle estimates" and include the three major greenhouse gases emitted by motor vehicles: carbon dioxide, nitrous oxide, and methane. Full fuel-cycle estimates consider all steps in the use of a fuel, from production and refining to distribution and final use. This gives a more complete picture of how using a particular fuel contributes to global warming.

Numerous assumptions and calculations are necessary to estimate full fuel-cycle greenhouse gas emissions in carbon dioxide equivalents. Because of this, estimates from different sources will vary somewhat. Our estimates are taken from the U.S. Department of Energy's GREET model, version 1.5 developed by Argonne National Laboratory. Additional information is available at:
http://www.transportation.anl.gov/ttrdc/greet/