I have a 1998 Honda Odyssey and I fold down the rear and one of the middle seats and fit a QX100 or S40 diagonally without problem. A car trunk with fold down seats is harder but usually doable depending on the car dimensions but can be awkward to lift in and out. Mine has gone in a pickup truck bed laying down loose for shorter trips. I would do it that way but strap it if I did that for a longer trip. I would not mount it in one of those axle mounts that you take off the front wheel because it would be a bother and would not use it on the rear axle for fear of twisting something. Over the tailgate might work but it is not a rugged mountain bike.
I have partially disassembled my Q by removing the seat, then rear wheel, then shock and rotating the rear swing arm under to overlap the front wheel. Or done the same with removing both wheels. This makes a much smaller package that packed in with the luggage much easier for a driving trip.