For a given journey, the energy consumed by a driver is at least 42 times more than by a cyclist, a bus passenger uses 34 times as much, and a train passenger 27 times as much. The cyclist requires less space than all but the train passenger and pedestrian. For journeys of up to 6 miles (10 km), the bike is definitely best for both rider and the planet. In terms of lifespan, life-cycle analysis at MIT shows that the bicycle consumes the lowest energy per passenger-mile across its entire life, compared to other forms of transport.
And that doesn't include the health benefits, which save how many $$ because it's hard to be obese when you ride a bike : )