This is the show car "Wildcat III" being mocked up.
I don't know if this is in Detroit or Flint. I guess I'll have to research Buick styling history now. This photo was in an in-house Buick publication showing all the aspects of building a Buick, so maybe this is building #84. I tend to think this was at G.M. design studio because this same publication showed a photo from the test center near Detroit.