I hate Nu-Metal, Pop and Rap, so I am always vocal about it. My friends don't take offense, but they also don't take my advice either.

Most of my friends don't like what I do. So we usually compromise.

well I say if you're in your car then you have the right to veto friends' music that you don't want to listen to while driving.. It's like your right as the driver.

My husband listens to tons of death meatal in the car and most of it I'm not into...AT ALL. But I put up with it cuz he's driving :)

You're not supposed to touch the music in my car if I'm in it.
failure to comply will result in a few things if not at least one

1) get out
2) all appendages will be removed
3) i'll turn the music up louder just to piss you off.

That rule applies to the car and living room or for your home theater system. If anyone tries to mess with it, tsk tsk.

Most of my friends have pretty good taste in music. Generally, if they're driving with me I'll try to avoid Merzbow or The Boredoms and play something I think they will enjoy at least a bit. But if they turn down my music or try to change it I'll kick 'em out of the damn car.

I play Wesley Willis and everyone's happy.

I've this one friend who's into Black Metal/Doom Metal, "Dark Ambient", Drone, Post Rock, Industrial, "Harsh Noise" and all that stuff, although his favorite artist is Nick Cave & the Bad Seeds. I might get into some of that stuff eventually.

A group of friends are into punk, NOFX, Offspring, Propagandhi, Misfits, Bad Religion, Rise Against, Against Me and all that, which I can relate to because I used to be way into it as well. And the rest like Led Zeppelin, RHCP, Muse, etc.

To sum up, my friends have decent taste, but not great.

For me it's all simple: my car or my house - my music. Something like my way or the highway :D