What a great move from BMW to gather up all those models before they're going to unveil the M5! I would've loved to have a tour at that place. Not many museums could be that fascinating

 

Ok, I looked it up on wikipedia:

Originally envisioned as a Ferrari competitor, only a single prototype BMW M8 was ever produced, equipped with a special 550 bhp (410 kW; 558 PS) version of the S70 engine, essentially a bored out version of the M70 with experimental multi-valve cylinder heads. A common misconception is that this engine powered the McLaren F1. However, when this was suggested to McLaren's designer Gordon Murray, the idea was rejected because the engine was too heavy and long for the McLaren F1. A completely new BMW engine was designed which has a closer resemblance to the later Euro S50B30 BMW M3 engine.

The project was eventually scrapped because BMW decided that there was no market for an M8. The only prototype ever produced (one that was reportedly not even road safe) was locked away by BMW in the company's Giftschrank (poison storage).[6] BMW and the M Division had strongly denied that the car was even a possibility since the initial stages of its development. A world exclusive feature in the February 2010 issue of BMW Car Magazine, however, revealed that the M8 prototype still exists in its entirety.[7] The car was unveiled for the first time in front of journalists on July 2, 2010 at the BMW Museum in Munich.[8]

While the M8 was never produced, it is interesting to note that the 850CSi was also tuned by BMW's M division. Aside from sporting an M-tuned engine (as identified by the S suffix instead of the M prefix that a non-M tuned engine would wear), the car's VIN identifies the car as being built by BMW Motorsport (identified by the WBS prefix) instead of BMW AG (WBA prefix). This effectively identifies the 850CSi as essentially a detuned version of the M8.[9]