01 · Overview
What remained of the M8
After BMW halted the real M8, the 850CSi became the fastest series production form of the 8 Series: the S70B56 — developed at M GmbH, identified by the “S” in the engine code — extracts 380 PS and 550 Nm from 5.6 litres of V12, available exclusively with a six-speed manual gearbox.
This was joined by a firmer suspension, lower aprons, four tailpipes and, on request, active rear-axle steering. With 1,510 units, the CSi is the rare collector’s item of the model line — prices have long since decoupled from the rest of the E31.
02 · History
Einordnung
- 1990 The M8 prototype with over 550 PS remains a one-off — the project is halted.
- 1992 The 850CSi launches as the civilian essence of the M8 programme.
- 1996 End of production — tightened US emissions standards seal the fate of the S70.
03 · In detail
In detail
Coupé
Identifying features: lower M aprons, four square tailpipes, 17-inch cross-spoke wheels — and the VIN begins with "WBS" as an M vehicle.
04 · Engines
S70B56 verified
M V12 based on the M70: more displacement, sharper valve timing, its own engine management. No relation to the McLaren F1 engine S70/2 beyond the name.
Technische Daten anzeigen
| Hubraum | 5.576 cm³ |
| Leistung | 380 PS (280 kW) at 5,300/min |
| Drehmoment | 550 Nm at 4,000/min |
| Bauart | V12, naturally aspirated, six-speed manual |
Wikipedia DE/EN, BMW E31
05 · Engineering
Engineering
Active rear-axle kinematics (AHK)
WBS instead of WBA
06 · Buying guide
Buying advice in brief
History is everything: S70 parts supply is feasible but expensive; AHK cars need specialists. Check bodywork condition (wheel arches, windscreen frame).
07 · The competition
The competition
Porsche 928 GTS
The other great Gran Turismo of the era — V8 versus V12.
Ferrari 456 GT
Same idea, Italian execution, double the price.
08 · Sources