Originally Posted by fuerein
If you want to get technical the driver of the car also burn calories just from driving, so that should be included in the total expenditure of the system.
This site lists driving a car as expending 125 calories an hour. Assuming the cross country trip is NY to LA, the distance (according to Mapquest) is about 2793 miles, at 65 mph, you would need to drive about 43 hours, getting a total of 5375 calories just to keep the driver driving.
No, supcom excluded the energy required in excess of the energy required for riding, so forget about the driver's energy usage.
But if we want to get
really technical, we would have to look at the true total system efficiency. That includes not only the efficiency of the fuels, but also the total energy spent during the production of the vehicles, and the energy spent manufacturing and transporting "wear and spare" parts. Here, we have to include the projected energy needs for the full life of each vehicle, divided by the total distance they end up travelling at the end of their usefulness. This extra energy needs to be added to the distance in the example supcom provided.
A typical car probably weighs around 100 times what a typical bike weighs. If we assume that that also means it requires 100 times more energy, the bike would have only 1/100 of the unit distance cost of the car. But if the bike travels 1/100 of the distance the car does during their respective lives, the unit distance cost becomes identical for both vehicles.
What the actual figures are, I don't know...