Background
BMW 850i Convertible (E31) is one of the rarest and most fascinating offshoots of the E31-generation 8 Series. It never reached series production, but the project progressed far enough to show that BMW seriously considered adding an open-top grand tourer to its new flagship coupé range. While the BMW 850i launched as a highly advanced V12 luxury coupé, the Convertible would have added an even more exclusive and emotional open-air dimension to the same concept.
An open-top 8 Series
During development of the E31, BMW investigated a Convertible version and ultimately built three prototypes. The cars were used for extensive testing, but BMW decided not to proceed with series production. Creating an open-top E31 was technically demanding because removing the roof from such a low and wide coupé required substantial body reinforcement and a completely new roof structure. The additional weight and high production costs increased the commercial risk of what was already one of BMW’s most expensive models.
Design
The 850i Convertible retained many of the most distinctive features of the E31 Coupé, including its low and wide body, long bonnet, pop-up headlights and powerful rear-end design. Removing the fixed roof changed the proportions considerably and gave the car the appearance of a classic luxury grand tourer. The clean side profile and low beltline of the E31 worked particularly well in open form, while the engineering challenge lay in preserving structural rigidity and safety without compromising the refined character of the 8 Series.
V12 engine and technology
The BMW 850i Convertible was technically based on the production BMW 850i and used its 4,988 cm³ M70 V12 engine. The engine produced 300 hp, or 220 kW, at 5,200 rpm and 450 Nm of torque. The prototype used a six-speed manual transmission and rear-wheel drive. Top speed was approximately 250 km/h. As in the production 850i, the strength of the V12 lay not only in its performance but also in its smooth and refined power delivery, which suited the character of a large luxury convertible particularly well.
Why did it not enter production?
Development of the E31 Convertible progressed far enough for prototypes to be used in real-world testing, but BMW stopped the project before series production began. The open body required additional structural reinforcement, increasing both weight and manufacturing cost. At the same time, the 8 Series was already one of the most expensive and relatively low-volume cars in the BMW range. The financial risk was therefore considered too high, and the open-top E31 remained a prototype project. A series-production BMW 8 Series Convertible would not appear until almost three decades later with the G14 generation.
850i or 850Ci?
The prototype is referred to in different sources as both 850i Convertible and 850Ci Cabriolet. It was developed at a time when the V12-powered E31 was still officially known as the 850i, before BMW later changed the production model name to 850Ci. BMW’s own historical material uses the designation BMW 850i Cabrio Prototype. For that reason, BMW 850i Convertible is the more historically appropriate name for the car, even though model manufacturers and later references sometimes use 850Ci.
Significance in BMW history
The BMW 850i Convertible demonstrates how ambitious the original E31 development programme was. The first-generation 8 Series remained a coupé in production form, but the three Convertible prototypes show that BMW seriously considered creating an open-top flagship as well. The combination of a V12 engine, open body and futuristic 8 Series design would have made it one of the most exclusive BMW models of the 1990s. Today, the 850i Convertible stands alongside the M8 prototype as one of the most intriguing examples of how much broader BMW’s original vision for the E31 could have been.
Model in the collection
The model in my collection was produced by Schuco as part of the PRO.R43 series. It was produced in a limited edition of 500 examples. Schuco also uses the designation BMW 850Ci Cabriolet for the model, while BMW’s own historical material refers to the prototype as the BMW 850i Cabrio. For this reason, the car is presented here as the BMW 850i Convertible (E31).
Technical data in brief
Year: 1990
Basis: BMW 850i Coupé / BMW 8 Series (E31)
Body style: two-door luxury Convertible prototype
Engine: M70 V12
Displacement: 4,988 cm³
Power: 300 hp / 220 kW @ 5,200 rpm
Torque: 450 Nm
Transmission: 6-speed manual
Drivetrain: rear-wheel drive
Top speed: approximately 250 km/h
Number of prototypes: 3
Special feature: a V12-powered open-top E31 developed to prototype stage but never put into series production
Photo of the real car. Source: carandclassic.com