BMW did have hopes for the 8. I remember when the 850CSi came out the market was amazed. The Germans were saying with this thing why would anyone want a Porsche.
For those of you who never heard of this, BMW did build an M8. The car you see below, was 1990 BMW M8 prototype #1 -- one and only. The project was then cancelled for many reasons and this prototype was destroyed.
The engine BMW used, the S70, easily made 550hp out of 6.0l and 12 cylinders. This engine, was then given to McLaren and used in the legendary McLaren F1. The Mclaren guys said they were able to get 1000hp at 9500-10000rmp from that engine. It's one of the best engines BMW has ever built.
The 850CSi, with a total production number of 1510 during Aug 92 - Oct 96, was actually a detuned version of the M8. Engine number of a 850CSi starts with an "S", which indicates M-origin. The VIN starts with WBS (BMW Motorsport) instead of WBA (BMW AG). THe 850CSi was indeed an M without the badget.