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. 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) and was reportedly destroyed. 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, though at the time of writing a malfunctioning engine management module still required attention before the S70/1 V12 could be declared in proper running order.
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). The 850CSi as essentially a detuned version of the M8.[4]