I use Radio 1 for my alarm. In the days of Sara Cox doing the breakfast show I used to claim it was because she was so annoying it would horse me to get up and turn it off. That's certainly still valid.
Car into work: usually nothing, I don't want a tune stuck in my head all day, and five live has a phone-discussion about their topic of the day. Only ill-informed belming shitfarmers are allowed to ring in, though.
At work, MP3 player when in the toilet, sometimes at lunch, batteries won't last all day.
Car home, anything but Scott Mills. Will listen to Radio 1 if it's just mindless dance stuff, otherwise five live (usually a sports discussion) or WM (excitable brummie sports discussion)