They are just codes that BMW uses to show how far a car is in the production process. 111 and 112 are early on. At that time, the car is still changeable. In other words, the can still have your dealer change the color, options, etc. Once the car goes 150, it is approaching production. At that time it is no longer changeable because they are lining up your parts for the production line. I believe 155 is actually "in production" but might be off on that one.