I am not mechanic, but I heard this on the cartalk radio show:
http://cartalk.com/content/puzzler/transcr...516/answer.html
Bringing a dead Bug back to life
TOM: When he opened the hood, he found a pair of coveralls, a spare tire-- and a jack.
RAY: He got into the car, and turned the ignition key to the "on" position. There was no point to turn it to "crank," because the battery was what? Dead.
He pumped the gas a couple of times, like you would do in one of those old cars to prime the carburetor.
He then jacked up one of the rear wheels, which are the wheels that receive power from this engine. He put the transmission in gear; probably -- I’m guessing -- third gear. If you put it in fourth gear the engine would turn too slowly. If you put it in first, it would be too hard to turn the engine.
What he simply did was turn that tire that was elevated off the ground by hand with the transmission in gear.
He begins to turn the wheel really fast. Once it began to turn, the engine actually started up and ran and that wheel began to turn on its own.
The reason the other wheel didn’t turn is because there's a differential, which will only send power to the wheel with the least amount of resistance.
Finally, of course, he would get into the car, take it out of gear, get out and lower the jack down, and if he was lucky he would drive to work without stalling.