The BMW E31 is the first generation of the BMW 8 Series. It is a grand tourer
built by BMW from 1990 to 1999 powered by either a V8 or V12 engine. While it did supplant the original E24 based 6 Series in 1990, a common misconception is that the 8 Series was developed as a successor. It was actually in an entirely new model class aimed at a different market, with a substantially higher price and performance than the 6 Series.
Development of the 8 Series began in July 1981, with both the final design phase reaching completion and production development starting in 1986. The 8 Series debuted at the Frankfurt Motor Show (IAA) in early September 1989. The 8 Series was designed to move beyond the market of the original 6 Series. The 8 Series had substantially improved performance, as well as a far higher purchase price.
Over 1.5 billion Deutsche Mark was spent on total development (2019 USD nearly $900 million). 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.
The 8 Series offered the first V12 engine mated to a 6-speed manual transmission on a road car. It was one of the first vehicles to be fitted with an electronic drive-by-wire throttle. The 8 Series was one of BMW's first cars, together with the Z1, to use a multi-link rear axle.
While CAD modeling allowed the car's unibody to be 3 kg (8 lb) lighter than that of its predecessor, the car 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. As a result, plans for the high performance M8 variant were dropped in 1991.
BMW pulled the 8 Series from the North American market in 1997, having sold only 7,232 cars over a seven year period. BMW continued production for Europe until 1999. The worldwide production grand total was 31,062. The base price for an entry-level 8 series in the early 1990s started in the US$70,000 range, which is US$134,241 in 2018.
The 840Ci was offered with two different engine packages. The first used the 4.0-litre M60B40 V8 engine having a power output of 286 PS (210 kW; 282 hp) and was produced from mid-1993 to late 1995. 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.
The 840Ci was available with a 5-speed automatic transmission, though European cars were given the option of a 6-speed manual transmission. The only external features distinguishing the V8 model from the V12 models were the quad round exhausts, which were square in the V12 models. The 840Ci stayed in production until May 1999.
The 850i was the first model of the 8 Series launched in 1990 with the 5.0-litre M70B50 V12 engine having a power output of 300 PS (221 kW; 296 hp). It was available with either a 4-speed automatic or a 6-speed manual gearbox.
There is some confusion over why and when the 850i became the 850Ci. The change happened around the introduction of the 850CSi and it is believed that BMW decided to include the "C" in the model name that denotes 'Coupe', just as two-door 3 Series cars alongside the 8 Series read 323Ci, 328Ci and so on. The confusion started when BMW installed the new M73B54 V12 engine in the car. This was not an immediate changeover, and indeed both the M70 and M73-engined cars rolled off the production lines side-by-side for about nine months in 1994, both named 850Ci.
As the displacement of the M73 increased to 5.4-litres and the compression ratio went up, the power output increased to 326 PS (240 kW; 322 hp).
As a top-of-the-range variant of the 8 Series, the 850CSi took over from the prototype M8 variant. The 850CSi used the same engine as the 850i, which was tuned so significantly that BMW assigned it a new engine code: S70B56. The modifications included Bosch Motronic 1.7 fuel injection, a capacity increase to 5,576 cc (5.6 L) and power increase to 280 kW (381 PS; 375 hp) at 5,300 rpm and 550 N⋅m (406 lbf⋅ft) of torque at 4,000 rpm.
The 850CSi's modified suspension included, stiffer springs and dampers that reduced the car's ride height. The recirculating ball steering ratio was dropped 15% over the standard E31 setup. The model also sported staggered throwing star wheels. The front and rear bumpers were reshaped for improved aerodynamic performance. Four round stainless steel exhaust tips replaced the square tips found on other models. The 6-speed manual gearbox was the only transmission option. In Europe, all 850CSi's came with four-wheel steering (AHK - Aktive Hinterachs-Kinematik, Active rear axle Kinematics), uprated 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 840Ci (4.0/4.4 L V8) models were equipped with a 5-speed automatic transmission or a 6-speed manual transmission. The 850i/850Ci (V12) models each use either a 4-speed automatic transmission or a 6-speed manual transmission, a 5-speed automatic transmission was fitted from mid-1994. The high performance 850CSi model only came with a 6-speed manual transmission.
2017 United States Environmental Protection Agency estimates for cars equipped with automatic transmission.
840Ci
850Ci
For the 850i, 1991 Sport Model specifically the On-Board computer will typically read 24.6L/100 km when the car is often used under heavy acceleration. These figures could be similar if not slightly less/more for more newer versions of the 850i Sport.
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