The BMW 635 CSI was the most powerful version of the first generation of the 6 series coupe at the time of its launch on the market in 1979.
It was a coupe faster and more comfortable than other GT vehicles on the market.

After the successful BMW 3.0 CS at the beginning of the ’70s, the German company needed a replacement. Paul Braq designed a new vehicle based on the already existing platform of the BMW 5-Series, which allowed the use of 4 and 6 cylinder engines. But for a performance coupe, BMW didn’t want to use an inline-four and chose only the inline-six units. Even though it was considered the two-door version of the 7-Series, it was a mix between the 5-Series platform and 7-Series design cues.

The first generation of the 7-Series and the 6-Series were designed by the same team and that is why they are similar in shapes. The shark-nose design and the descending trunk line were similar. But unlike the executive sedan, the 6 Series featured frameless windows for the doors and only two seats in the back. The dashboard featured a centers stack tilted toward the driver and the instrument cluster featured four dials. It was the same layout kept by the German car-maker for over two decades: coolant temperature, tachometer, speedometer, and fuel level.

The engine was a 3.5-liter inline-six with a broad torque range that helped the car pull in every of its standard 5-speed gearbox. The up-mounted gear-stick was one of its main advantages over other luxury coupes on the market. It was available with an automatic transmission as well, named 635 CSI A.