An interior, exterior model cost easily twice as much to make. Apparently the car was cast, and the fiberglass model made, but people were not sure it was really going to go into production,. This is a classic Dave Holls design. He was director of design at Opel at that time.. A beautiful car no doubt. And I am sure that George Galion had a lot to do with it as he was Dave's assistant, and in charge of all of the design.