You beat me to it! I was going for trying to piece it together using some of the clues, small bumpers meant before huge bumpers were fitted to cars destroying the lines, fuel filler door on front wing (fender) suggested rear engine. B pillar! . I’d say Chevrolet Corvair Monza 1965.Mid 60's Chevy Corvair
I believe the “unsafe at any speed “ causes were largely addressed with the modifications to the rear suspension of later models, but by then the damage, in more ways than one, had been done.
Part of it.