But even lower accelerations will glue you to the seat because gravity acceleration affects every part of your body. Where as the car grabs you by the butt and yanks you forward.

The feeling of weight we associate with gravity is not distinguishable from elevator-style or car-style acceleration (not counting vibrations; or tiny gradients in the field). You don't feel gravity gluing you to the ground, you feel the ground continuously shoving you skyward to stop the free fall.

See: equivalence principle https://en.wikipedia.org/wiki/Equivalence_principle