That´s a little bit tricky. I´ve found this photo in May 2009, described as "Porsche_15" at some website.
But as I´m quite sure it is not a 904 GTS or anything alike, I think it must be some GM concept car, maybe a pre-presentation version of the Corvair Monza GT.
And - as I hope I am not totally wrong, a photographer named "Madler" was active for GM in those days...
The man might be Norman J.James.