@tsarstepan,
When I had a car on road trips I would often sing, but I noticed I would unconsciously accelerate the speed of the car, so I had to be careful.
The singing in the shower bit was taken to it's ultimate absurdity in Woody Allen's movie To Rome with Love. A man becomes a famous opera singer, but only when he's in an actual shower on stage.
You'd rather drive or be a passenger on car trips.