On the Buses

[Unregistered]

My friends and I have been mulling over this for a few days and are yet to come up with an answer. Why do we say "I am on the bus" or "I am on the train" but we say "I am in the car"?

[Casiopea]

You walk on (i.e., step onto) a bus; you get in (i.e., crouch inside) a car.

[Anglika]

It's a nice one, isn't it?

I can only conclude (in relation to transport) that "on" is used for public transport which carries many passengers, and "in" is used for transport which carries a limited number.

Oops - sorry, Cas. Your explanation is beautifully clear.