Somebody needs to explain what a "post car" is - new term to me!
As mentioned, it's a 2-door car with B-pillar, officially called a 2-door sedan. With these Chevies the "sedan" models actually have an extra ~2 inches of headroom or top height, and '60s Chryslers are that way too.
Compared to a 2-door hardtop.
In the 4-door world, they're just referred to as a "4-door" or "4-door sedan".
4-door hardtop.