I am hoping you can help me.
Please could you explain why we say
in a car or taxi, but
on a bus, train, ferry, plane etc
Many thanks for your time and I look forward to hearing from you.
In and on are used with means of transportation[and not only]: in is used with a car, on with public or commercial means of transportation:
in the car
on the bus
on the plane
on the train
on the ship
Some speakers of English make a further distinction for public modes of transportation, using in when the carrier is stationary and on when it is in motion.
My wife stayed in/on the bus while I got out at the rest stop.
The passengers sat in/on the plane awaiting takeoff.