Not me though, ever.

“1u. Used to indicate a means of conveyance: ride on a train.”

http://dictionary.reference.com/browse/on

The basic reason may simply be that you walk onto these vehicles (unlike a car).

The point of “in” would, in this case, be “enclosure”, emphasizing that you are inside and surrounded by something. That may, in fact, be the case for some of these large vehicles. But it is NOT the point of the expression.

notsolucky: How about, “I am going to shower.”?

That’s fine, I am very sarcastic, too as if you couldn’t tell.

….although i wouldn’t know how else to state those ((sarcasm))

timberwolf – true statement…i understand there are correct ways of saying it. i guess i should have stated my sarcasm in that comment