iPhone SE music playback when connected in car

I use my iPhone SE for navigation. When I connect it in the car, when it gets a good signal if often decides to play some music source (BBC sounds, Music). It often does this after I have started driving so there is nothing I can do to stop this other than turning off the car audio (which means I lose navigation). Is there some way to disable this feature.

Music is even worse - can randomly pick something stupid (say the piano part of a song and play that on loop). There is literally no circumstance under which this behaviour is useful.

(Vehicle is a BMW 5 series if this is relevant).

[Re-Titled by Moderator]