Excellent post Big Windy!! I just wanted to add that people can see something very similar when visiting the Spartanburg plant in SC. Of course, you will not see M3 cars coming to life there....but you will probably be able to spot some Z4 M models and other X5 and X6! What amazed me most was the fact that the cars are truly built in the order the sales order are posted in the system. A direct consequence is that you will not see a batch of white cars, then some black, etc... but you will truly see a mix of colors that are just a function of when the cars were ordered (amazingly, it takes less than 30 seconds to BMW to switch the set-up of their pain shop when switching from color A to color B!!).
Concerning the Quality checks, it seemed that all cars had to undergo a "static" test where the engine would be ramped up according to a specific standard. Depending on the outcome of this test as well as based on a certain frequency, some cars would be further inspected and/or test driven on a track.
Anyhow, just like Big Windy, after I had done the plant tour, I came to appreciate even more my car. BMW FTW!!!