- Where are you?
- I am in a car.
- Where are you?
- I am in the underground.
- On what are you going/driving?
- I am driving/going on a car.
- On what are you going/driving?
- I am going by the underground.
- I am going by bus.
- I am going by train.
- I am going by tram.
- On what are you going/driving?