You get ‘on’ a bus or train, but you get ‘in’ a car or taxi
How to not mix them up (for those who might be learning English): If you walk upright when boarding, you’re getting on. If you sit into a seat from the door, you’re getting in.
So, for example, you also get *on* a plane or boat, and *in* a carriage.
Oh, that is a good distinction.