Depends what mood I'm in and the journey, for long drives I prefer songs with little or no lyrics. And ideally dubstep or drum and bass. Nothing too heavy, just nice and mellow.
But then sometimes I want a darn good sing a long, for which I choose Audioslave, Muse, Foo Fighters, Newton Faulkner etc.
Others I want heavy dubstep, Feed Me, Knife Party, I'va also got a UKF CD I borrowed from a friend that I stick on.
Other times when I just really want to get home I don't listen to music at all.