Oh, well. NOW it gets difficult. But I would hazard a guess that it is the product of one of the carozzeria houses of Italy.
Lessee: Bertone, Ghia, ItalDesign, Guigaro, PininFarina. Those are the onliest ones I can think of.
Not weird enough to be Bertone. Ghia worked mostly with Ford.
I am going to say PininFarina, because it was used from time to time by GM..
But it IS a Corvair chassis under that rather stylish body, right?