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BMW 8 Series (E31)
Overview
Manufacturer	BMW
Production	1989–1999 31,062 built
Assembly	Germany
Designer	Klaus Kapitza (1986)
Body and chassis
Class	Grand tourer (S)
Body style	2-door coupé
Layout	FR layout
Powertrain
Engine	4.0 L M60 V8 4.4 L M62 V8 5.0 L M70 V12 5.4 L M73 V12 5.6 L S70 V12
Transmission	4-speed automatic 5-speed automatic 6-speed manual
Dimensions
Wheelbase	2,685 mm (105.7 in)
Length	4,780 mm (188 in)
Width	1,854 mm (73.0 in)
Height	1,341 mm (52.8 in)

The BMW 8 Series (chassis code: E31) is a Grand Tourer built by BMW from 1989 to 1999 powered by either a V8 or V12 engine.

While it did supplant the original E24 based 6 Series in 1991, a common misconception is that the 8 Series was developed as a successor It was actually an entirely new class aimed at a different market, however, with a substantially higher price and better performance than the 6 series

The E31's mutually related successor is the BMW E63, as well as the BMW i8 in 2015. While they are not direct model derivations of the "8xx" lineup, they are the only other touring cars produced by BMW after the E31's introduction in 1989 with as much size, performance options, and technology that can be classed as anything similar to what the E31 lineup offered for its age.

Furthermore, the E31 was BMW's flagship car and had an electronically limited top speed of 250 km/h (155 mph). There has never been an ungoverned test for top speed but it's unlikely the E31 would've exceeded 288 km/h (179 mph) even with the 372 HP engine.

History of development

Design of the 8 Series began in 1984, with the final design phase 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, however, as well as a far higher purchase price.

Over 1.5 billion Deutsche Mark was spent on total development (2008 USD nearly $1 billion). 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 0.29, a major improvement from the previous BMW M6/635CSi's 0.39.

The 8 Series offered the first V-12 engine mated to a 6-speed manual gearbox on a road car. It was the first car to feature CAN bus—a form of multiplex wiring for cars that is now an industry standard. It was also 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 8 lb (3 kg) 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 pillarless "hardtop" body style, which lacked a "B" post. This body style, originating in the United States in the late 1940s, was abandoned by Detroit in the late 1970s.

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 M8 supercar were dropped in 1991.

BMW pulled the 8 Series from the North American market in 1997, having sold only 7,232 cars over seven years. BMW continued production for Europe until 1999. The ultimate worldwide production total was 31,062. The base price for an entry-level 8 series in the early 1990s started in the $70,000 range, which is $128,321 in 2016.

Prototype models

830i

The 830i was a prototype that did not reach production. As the potential entry-level model, the 830i was to use the 3-liter V8 with 218 PS (160 kW; 215 hp) from the 530i and 730i, known internally as the M60B30. Eighteen cars were produced, thirteen of which had an automatic gearbox fitted. The model was dropped in favour of the 840Ci and almost all of the 18 cars were dismantled; one car is in a BMW museum.

850i Cabrio

The 8 Series had been planned from the start with a convertible version in mind. Although the 850i Cabrio was developed to production readiness, it never went into production. At a relatively late date it was decided that this model was unlikely to recover its development cost. A prototype in red resides in the BMW Museum in Munich.

M8

Originally envisioned as a Ferrari competitor equipped with a special 550 bhp (410 kW; 558 PS) version of the S70 engine, essentially a bored out version of the M70 with experimental multivalve cylinder heads. A common misconception is that this engine powered the McLaren F1. When this was suggested to McLaren's designer Gordon Murray, however, the idea was rejected because the engine was too heavy and long for the McLaren F1. Rather, variations on the original S70 used on the 850csi, the S70/2 and S70/3 were used for the McLaren F1. (The variation used on the M8 prototype was the S70/1 engine.)

The project was eventually scrapped because BMW decided that there was no market for an M8. The only prototype ever produced (one that was reportedly not even road safe) was locked away by BMW in the company's Giftschrank (poison storage). 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. The car was unveiled to journalists for the first time on July 2, 2010 at the BMW Museum in Munich. The only public showing of the car happened on August 17, 2012 during 'The Legends of the Autobahn' car show held in Carmel, California. The car was specially shipped from Germany for the appearance.

While the M8 was never produced, it is interesting to note that the 850CSi was also tuned by BMW's M division. Aside from sporting an M-tuned engine (as identified by the S prefix instead of the M prefix that a non-M tuned engine would bear), the car's VIN identifies the car as being built by BMW Motorsport (a WBS prefix) instead of BMW AG (WBA prefix). Per BMW's own protocol, the 850CSi as marketed was essentially a de-tuned version of the putative M8.

Motorsport

The 8-Series is a very rare car to see in any form of motorsport. One of the most successful examples was built by Wagenstetter Motorsport however, and, until recently, was raced in the Nurburgring VLN endurance championship. It’s based on an 840i, but now has an E39 M5 5.0-litre V8, which has 555 bhp (414 kW; 563 PS) and 472 lb·ft (640 N·m) torque, and a six-speed gearbox from the same car.

Powertrain and production data

Model	Years	Engine code	Power	Torque	Production total
840Ci	1992–96	M60B40	210 kW (286 PS; 282 hp)	400 N·m (300 lb·ft)	4,728
840Ci	1995–99	M62B44	210 kW (286 PS; 282 hp)	420 N·m (310 lb·ft)	3,075
850i	1989–94	M70B50	220 kW (299 PS; 295 hp)	450 N·m (330 lb·ft)	20,072
850Ci	1992–99	M73B54	240 kW (326 PS; 322 hp)	490 N·m (360 lb·ft)	1,218
850CSi	1992–96	S70B56	280 kW (381 PS; 375 hp)	550 N·m (410 lb·ft)	1,510

Transmission

The 840Ci (4.0/4.4l V8) models were equipped with a 5-speed automatic transmission or a 6-speed manual transmission. The 850i/850Ci (V12) models each carry either a 4-speed automatic transmission or a 6-speed manual transmission, a 5-speed automatic transmission was fitted from mid-1994. The 850CSi model only came with a 6-speed manual transmission.

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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