There is a famous story written by Peter Egan which compares the fuel mileage of a Honda Cub to that of an athlete riding a bicycle. I'll save all of the details out (check out Egan's book "Leanings" if you must know it), but the consensus of the trip was that the 168 miles per gallon that the Cub got made it more efficient than the bike rider. That may not be entirely true, but it is impressive mileage. Honda touted that the Cub could do even better when ridden by your grandmother, and now that the machine is fuel-injected, the mileage may be better still. What's more is that emissions could also be reduced by a significant margin. Although no longer sold in the United States, used Cubs are not difficult to find, and the 50cc four-stroke engines are just as miserly as ever. If you are serious about reducing your gas bill, maybe a visit to your local classified section could have you happily commuting at over 100 miles per gallon by spring-time.
[Source: Honda via The Kneeslider]