The C111 is most likely a Mercedes with which you are not familiar. It surfaced in 1969 at the Frankfurt Auto Show and many suspected that it was a successor to the mighty Gullwing. Alas, it was not, and nor was it designed for the general public. In a way it is the most important car MB has ever built— in short, the C111 is a design and engineering study built by Mercedes to test out its new ideas. It was an experimenta' vehicle used to test glass-fiber-reinforced plastics, a version of Felix Wankel's famed rotary engine, aerodynamic efficiency, and nifty features like doors hinged at the roof. The C111 evolved over the years along with Mercedes' developing technologies, and a site smitten with cars of the Teutonic variety explains fully and complements its words with plenty of images.