Pouring away gas

[...] When you figure in that your mass compared to the car’s mass is about 5%, that leaves less than one percent of the energy in the fuel for transporting YOU. Let’s be generous and say it’s actually one percent. [...]

[...] When you convert the amount of energy needed to bike a mile and convert that to the car’s miles-per-gallon equivalent, riding a bicycle has a “miles-per-gallon” of about 650. [...]

http://www.geektieguy.com/2007/01/26/more-on-pouring-away-gas/