A couple of other random facts from the show (I've only seen the last half so far - I happened upon it while channel surfing):
(skip this post now if you prefer to see these on the show first)
They run the plain bodies through what look like car wash rollers to remove dust before painting, except the rollers are made from ostrich feathers.
They use electrostatically-charged paint/primer to make it stick on the grounded body and to minimize waste. The painting process increases the body weight by 20 pounds.
When the body hits the paint booth, a nearby contractor (Lear) is signaled to build the seats for this car (Just In Time manufacturing). This is 14 hours before assembly. At six hours before assembly, Lear is signaled to deliver the seats to the BMW factory. They're trucked over from Lear five miles away.
They use a hovercraft lift to hold and carry the exhaust system as it is installed in the overhead chassis. The hovering allows the unit to be repositioned easily and to slide along the floor with the chassis as it moves down the assembly line.
They heat the wiring harnesses to make them more flexible for installation on the assembly line.
The BMW guy said that for years they had been telling people that the roundel represented a propeller from BMW's heritage of building aircraft motors, but they've since determined that it's simply the colors of the Bavarian flag, as shown in the flag's blue/white checker pattern (hey, he said it, not me...).