Yes! It is the VW Porsche Type 700, "Grossraumwagen" from 1956/57. At the development-stage of the puzzle car, a 600ccm-engine had been planned to be used. At later stages of the type 700 project, beetle front and rear suspension and the well known 1200ccm 4 cylinder boxer engine should replace the previous ideas.
I never heard about Graf Goertz to be involved in this project?