WheelchairDriver

For anyone in a chair it means nothing.
I see many different figures from 38" on up to 43" in the specs of different vehicles.
I doubt there is ONE seat height these figures are derived from.

I think it means from floor (57 inches in my van) or doorway entrance (54 inches).

Well dodge shows 39.8", toyota 41" and honda 38.3". When you add a 10 or 14" drop ya don't get figures like these in the link.
http://www.braunability.com/which-minivan.cfm

http://www.braunability.com/which-minivan.cfm

Don't see headroom. Only height in various positions. Quite useful that page.

Headroom figures are from MFGs sites. Adding 10-14" drop that is way short of Braun's figures. Thinking the MFGs measure headroom off the seat cushion but whats that 8-10". Anyway the Nissan nv200 is taller than the minivans with a cargo height of 53" and that should be like an 8" drop in a minivan. If you're short it may be enough without lowering the floor.

Could be. But normally you don't want your head almost touching the top, and door entrances are around 4 to 6 inches lower that the interior?