Citroen GS Birotor

Citroen GS Birotor

The Citroen GS Birotor is one of the most fascinating and rarest production cars in Citroen's long history. Produced for barely a year between 1973 and 1975, the Birotor married two revolutionary automotive technologies: Citroen's hydropneumatic suspension and the Wankel rotary engine. Only 847 were built, and Citroen's subsequent attempt to buy back and destroy most of them makes surviving examples extraordinarily rare.

The Birotor used a twin-rotor Wankel engine developed by Comotor, a joint venture between Citroen and NSU of Germany. Displacing 1,990cc in equivalent terms, the engine produced 107 DIN horsepower and 135 Nm of torque. The rotary engine was remarkably smooth, virtually vibration-free, and compact, making it an ideal match for the GS's engine bay. The power delivery was silky and progressive, with the engine willing to rev freely to its redline.

The Birotor came exclusively with a three-speed semi-automatic C-Matic transmission, which used a torque converter in place of a conventional clutch. This was the only transmission available, as Citroen did not develop a manual gearbox mating for the Comotor engine. While the three-speed unit limited the car's potential, it provided smooth, relaxed driving that complemented the rotary engine's character.

The rest of the car was pure GS, which meant hydropneumatic self-leveling suspension providing a magic carpet ride, power-assisted inboard disc brakes all round, and the elegant fastback body designed by Robert Opron. The Birotor sat slightly wider than the standard GS to accommodate the engine's auxiliary cooling systems, and wore distinctive alloy wheels unique to this model.

The Birotor's downfall came from the 1973 oil crisis. The rotary engine's inherently higher fuel consumption made it commercially unviable in a world of expensive petrol. Additionally, Citroen itself was in severe financial difficulty, and the costs of the Comotor joint venture were contributing to its losses. When Peugeot acquired Citroen in 1974, one of its first decisions was to terminate the Birotor program.

What followed was remarkable. Citroen offered to buy back all sold Birotors, and reportedly crushed the majority of returned cars. Of the 847 produced, it is estimated that fewer than 200 survived this recall program, making the Birotor one of the rarest mass-production Citroens in existence. The cars that survived were kept by owners who recognized their historical significance and refused to return them.

Today, the GS Birotor is a highly prized collector's car, representing a unique confluence of revolutionary technologies. Finding Comotor engine parts is the primary challenge for owners, though a dedicated community of enthusiasts has developed expertise in maintaining these remarkable engines.