Probably the only way to get the headliner (flat) into a sedan is to take off the windshield. so they went in the door. The windshield is a big deal.. better the door than the windshield...
At least the Hatch they probably can go in the hatch?
I can see taking out the front seats. but the rear fold down...
The A B and C trim also would have to go.
Then the headliner now has airbages in it too..