[8] BMW used CAD tools, still unusual at the time, to design the car's all-new body.

Combined with wind tunnel testing, the resulting car had a drag coefficient of Cd=0.29, a major improvement from the previous BMW M6/635CSi's 0.39.

However the production 8 Series was significantly heavier when completed due to the large engine and added luxury items—a source of criticism from those who wanted BMW to concentrate on the driving experience.

Some of the car's weight may have been due to its pillar-less "hardtop" body style which lacked a "B" pillar.

Sales of the 8 Series were affected by the global recession of the early 1990s, the Persian Gulf War, and energy price spikes.

BMW pulled the 8 Series from the North American market in 1997, having sold 6,920 cars.

From mid-1995, production phased in the newer 4.4-litre M62B44 V8 engine, which had better fuel economy and more torque, though power output remained unchanged.

[16] The 850CSi's modified suspension included stiffer springs and dampers that reduced the car's ride height.

In Europe, all 850CSi's came with four-wheel steering (AHK - Aktive Hinterachs-Kinematik, Active rear axle Kinematics), upgraded and ventilated brakes with floating front discs, rear differential oil cooler, engine oil cooler, two-tone interior, sports seats, and reshaped mirrors.

In the United States, the cars instead received "BMW Motorsport" writing on the doorhandles.

Production ended in late 1996 because the S70 engine could not be modified to comply with new emission regulations without substantial re-engineering.

The M8 was originally envisioned as a Ferrari competitor equipped with a special version of the S70 engine, with modifications including a displacement increase to 6064 cc, dual overhead camshafts for each cylinder bank, individual throttle bodies with roller valves, four valves per cylinder, carbon fibre intake manifolds and continuously variable valve timing.

As a result, it was estimated the M8 would achieve a top speed of 320 km/h (199 mph), power output is 471 kW (640 PS) and its torque is 650 N⋅m (479 lbf⋅ft).

The project was eventually scrapped because BMW decided that there was no market for a high performance variant of the 8 Series primarily because of the on-going economic recession of the 1990s.

The only prototype ever produced (one that was reportedly not even safe for normal road usage) was locked away by BMW in the company's Giftschrank (poison storage).

[26] 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.

[27] The car was unveiled to journalists for the first time on July 2, 2010, at the BMW Museum in Munich.