Originally Posted by zeytoun

-1 gallon of gasoline creates 19.8 pounds of carbon
-314 million metric tons of carbon produced annually by cars in the US
-driven 2.6 trillion miles, at a fuel efficiency of 19.6 mpg
http://www.ens-newswire.com/ens/jun2...6-06-28-03.asp

Tour de France riders get about 300 "mpg" (one gallon of gas has 3100 calories, which will take these guys 300 miles, on average)
An efficient, 15mph cyclist gets over 900 "mpg"
http://auto.howstuffworks.com/question527.htm

So, if some schmuck argues that bicyling uses energy too, you can shoot back, "yeah, 2% of the energy that the average US car does."