From BringATrailer.com: http://bringatrailer.com/2009/07/15/...en-gs-birotor/

Most people think of Mazda or NSU when it comes to Wankel engines. Few people know that Citroën also had a brave (and brief) attempt at Rotary engine development. This 1974 Citroën GS Birotor is one of the very few surviving examples. Find it here on Ebay in France with a starting bid of €3,000.



In 1967 Citroën started an alliance with NSU to build rotary engines under the name Comotor. Initially a series of 267 experimental Wankel engined, Citroën Ami-based coupes were built and made available to a group of faithful customers. After the experiment was over the cars were taken back by the factory and supposedly all destroyed, though in fact at least a couple of cars escaped the crusher and are still in existence. In 1974 Citroën started offering a production car with rotary engine: the GS Birotor with an engine that was very similar that used in the NSU Ro80.



The Wankel engine transformed the performance. The normal GS was a supremely comfortable but hopelessly underpowered car, in the Birotor sub-10-seconds 0-60 times and a 175 kph top speed lay within reach. And all this maintaining the superb ride comfort and roadholding the GS was known for thanks to the hydropneumatic suspension. Unfortunately not only performance was impressive, so was oil and fuel consumption. This was not good news in a time when the world was hit hard by the oil crisis. At the same time Citroën hit financial turmoil and could only be saved by a Peugeot takeover. Peugeot immediately put an end to all Citroën eccentricities, and that included the Comotor experiments. Fearing high and complicated warranty claims Peugeot made all existing GS Birotor owners an offer they couldn’t refuse and sent all thus reclaimed cars to the scrap yard. For this reason only a handful of the 847 Birotors that were ever built survive.



The engine is turning over but would need recommissioning, but thanks to the NSU link parts availability should be OK. We would consider slotting in a Mazda engine, but in a car this rare we think originality is a real issue. The seller claims there is only surface rust on the body and no rot on the underside, but as these cars were notorious rotboxes we would like to verify. The interior looks fine and all other mechanicals should be easy to replace as the GS has a big and faithful following in Europe.



This would make a very interesting project, as the car appears to be mostly complete and not too far gone. The result would be an incredibly rare car that delivers a truly wonderful driving experience. Citroën built some seriously weird cars in their day, and this may just be the one that surpasses them all.