But there's more! The Bertone-built Testudo was styled by the great Giorgetto Giugiaro, apparently the first design for which he had a free hand. No doubt that was due to its show car status -- a production design imposes many more constraints on a stylist.
The Testudo link suggests that General Motors supplied the Corvair (that Bertone shortened) and presumably funded the project.
Despite its Giugiaro heritage, I don't consider the Testudo a very good design. See the captions below for my thoughts.