When a polluting vehicle is replaced with a newer more fuel efficient vehicle it makes a big difference to our environment. For example. Saving one gallon of gasoline per 100 miles saves 20 pounds of carbon dioxide, which is approximately one ton of carbon dioxide every 10,000 miles of driving. An improvement from 14 MPG to 25 MPG saves 3 gallons of gas per 100 miles, or 3 tons of carbon dioxide in 10,000 miles of driving. The replacement of older vehicles also reduces other non-greenhouse pollutants.