This is a 1964 Buick Wildcat with a body mostly made of fiberglass.
It was done by Don Mitchell who was I believe the head of Mitchell-Bentley Corp. who owned Ionia Mfg. Co.
It was an exercise to determine the feasability of the materiel for mass production. Evidently, it did not pass the test, but it did save 800 lbs. in weight on this particular car.
I believe the car still exists in a museum. I can get that info if necessary. Edit: The LeMay Museum.
Bill