I apologize for posting later than normal. Windows decided to perform an update when I sat down to finish this piece, so I lost around 45 minutes this evening.
The most important part of an automobile is how to power the wheels (or belt, if one talks of a snowmobile). What ever device does this must fulfill several requirements, which we shall look into later.
A device to propel a car must do several things, depending on the complexity of the automobile. It must produce enough power to overcome internal friction, to overcome air resistance, to overcome rolling resistance of the tires, and a couple of other things as well. Because of differences in combustion engines and battery operated motors, each type will be discussed separately.