I don't understand people's affinity with their car radios. I don't care what my passenger or the driver wants to listen to, the only issue I have is if it's really loud or so low to the point that it might as well be off, because then it just sounds like white noise.
A big annoyance I have is when someone borrows my car then returns it with the air on 90/60 degrees, fan on full blast (my car's fan is extremely loud) and the music cranked up to max. Now that really pisses me off.
I typically keep my car on one radio station (whose morning show I utterly loathe, but I either turn it off or grit my teeth through it for the morning commute) at a moderate volume, unless a song comes on that I like, then I turn it up.