We say:
"I got off the train"
"I got off the bus"
"I got off the airplane"
So, why is it we then say: "I got OUT of the car"? Why don't we say "I got off the car"?
If I said I got off the car, this would imply I was sitting ON the car, not IN it.
We even "get OFF a boat". But we get OUT of a car.
This language of ours is very weird, and it often doesn't make any sense.