The information used to calculate the environmental impact is based on figures from Environmental Defense,a leading national nonprofit organization representing more than 500,000 members.

600:
Average amount of gasoline consumed by one U.S. car each year.

12,000 pounds:
Amount of carbon dioxide emitted from one U.S. car each year.
(20 pounds/gallon)

240:
Number of trees needed to absorb the 12,000 pounds of carbon dioxide emitted from one U.S. car each year. (50 pounds/tree)