Rallye Shop was also known as Rallye Bitter. Erich Bitter, the son of a bicycle shop owner in Schwelm (close to Wuppertal), was successful cyclist until he developed a health issue. So he switched to racing Abarths, Volvos, Saabs and Opel in the 50/60ties (the bicycle shop must have been rather profitable...). At that time he started Rallye Shop and was pretty quickly the No.1 in that niche in Germany, Switzerland and Austria. Thru racing, he knew Bob Lutz, then the Opel/ Vauxhall CEO. As Opel wanted to promote their 2. Gen Admiral V8 against Daimler and BMW, they created the idea of a sports coupe on the Admiral chassis. The result was the Bitter CD (Coupe Diplomat) despite the oil crisis in 1973/74, Bitter was really successful and sold 400 ( I think..). Later, he did similar on the Senator I6 models. Bitter is 87? now, but still active.