I've just read on a not realiable site:
get on/get off is used for: a bus, a train, a subway, a plane, a ship, a boat, a motorcycle, a bicycle
get in/get out of is used for:
a car, a taxi
Do you confirm it?
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
I agree- they're the prepositions I'd use. I'd also use get in a van/truck/lorry.