Came across this a little while ago, thought I'd share it. It's a technical article written by ex-BMW Motorsport boss Dr Mario Theissen.
It's mostly in the context of the development of BMW F1 engines, but it does put into perspective the climate of development of the engines in the early...
If money was no object, and fuel is for free
M760Li:
V12, 6592 cc, xDrive
610 hp, 800 Nm
0-100 km/h 3.7 secs
M550i:
V8, 4395cc, 462 hp, xDrive
462 hp, 650 Nm
0-100 km/h 4.0 secs
Interesting how BMW is using an updated version of the P65 4.0 Liter N/A V8 (code named now P66) with 480 HP. No TT i6. Probably the Z4 GT3 would be updated with this engine.
http://www.bmw-motorsport.com/en/cars/bmw-m4-dtm.html