Opel CD Concept, 1969. Designed by Erhard Schnell (1927-2020) while he was head of Opel Advanced Styling Studio, the CD referred to Coupé Diplomat, the Diplomat was Opel’s flagship large saloon and was powered by a 327ci Chevrolet V8. The CD was never put into production by Opel but the design was adapted by Bitter for the Bitter CD.