The E31 BMW 8 Series Coupe was built for 10 years from 1989 until 1999, and according to my research, 30,621 units were sold.
Precisely 24 of these hand-built modern classics were assembled at BMW’s Rosslyn plant in South Africa. The reason for this was tax related; it was cheaper putting the cars together there, than importing them into SA. More than two-thirds were fitted with the V12, and just four came with a 6-speed manual transmission.
This particular car wasn’t one of the 24 locally-assembled cars; it was imported by the owner from the UK in full stock trim. Being an 850Ci variant, it was originally fitted with the 5.4L M73B54 V12, which produced 322hp and 490Nm.
The BMW’s stock form was very short lived in the hands of its new South African owner. Driving the 850 for the first time, he was left disappointed with the V12’s sluggish and uninspiring performance compared to modern cars. That sparked an idea…
Working with Wessel at Motor Cade Motorsport in Bellville a wicked plan was hatched, one that would give the 850Ci a new lease on life with E63 M6 underpinnings.
From the outside, the car doesn’t look too different from the way it left the factory, but if you look carefully you can easily see the changes. Automatic Xenon headlights were retrofitted into the existing housings, automatic rain-sensing wipers replace the originals, and OEM rear park assist sensors were installed into the bumper along with a rear-view camera.
The stock mirrors were replaced with fully-functional heated electric M6 items – two of many parts swapped over from an E63 donor car.
That includes the entire M6 drivetrain, including the electronic differential, along with the front and rear suspension featuring electronic dampers. Driving assists such as ABS and traction control were also coded to work flawlessly.
As you might expect, this wasn’t a simple job. Extensive surgery was required, and along the way new floors and custom-built suspension braces were fitted.
Once you get inside, you really feel like you’re in an M6, and a modded one at that. The 850 dash was completely removed and an original E63 dash was cut and trimmed to fit perfectly.
There’s carbon fiber everywhere, including on the M6 multi-function steering wheel with electric tilt.
Every single function and electronic module the M6 came with has been programmed to work in the 850, including the start/stop button, auto windows, cruise control and even the heads-up display system.
Wessel also installed the much newer NBT version of BMW’s iDrive system, with performance gauges, navigation and automatic climate control.
Lastly, the door panels and seats were retrimmed, the latter retaining their power and heating functions.
Getting the S85 V10 engine from the M6 to fit and work was one of the biggest challenges, both physically and from a technical standpoint. To accommodate the motor, the firewall had to be cut and a custom steel bonnet had to be built.
Although the donor engine was in good condition, Wessel wanted to ensure there’d be no trouble down the line as S85s are known to run bearings, even at relatively low mileage.
The motor was completely rebuilt with forged pistons, forged con-rods, and race bearings. A full exhaust was also built for the car, to help let the V10 sing. Final power output is a dyno-measured 493hp and 491Nm.
To put the power to the wheels, the standard M6 7-Speed SMG gearbox was used, and it works flawlessly. A manual M6 gearbox would’ve really made this car insane, but they were only offered in North America from 2007 onwards, in very limited numbers, so finding one would’ve been almost impossible.
Nonetheless, the SMG box makes driving really easy. The 850 was meant to be a cruiser anyway, so an auto box suits it just fine in my opinion.
The wheels are 20-inch Vossen CV5s in a machined matte graphite finish, and wrapped up in Falken Azenis FK458 tyres, 255/30R20 up front and 295/25R20 out back. For improved stopping power, M6 discs and calipers were fitted front and rear.
This build took hundreds of hours to complete, but if you look at the car and take a spirited drive in it, you can see how it’s been totally worth it. And further to that, Wessel said that if you took this car to a BMW dealership, you could service it just as you would any other E63 M6.
The owner of the car has enjoyed it for some good time now, but he’s looking at some new projects and doesn’t want this car to just sit, so he’s put it up for sale. I’m sure it won’t go cheap, but whoever snaps this up will definitely be getting something awesome.