I just got SatNav for my phone - CoPilot Live - for £25 you can't go wrong, and it's far cheaper than stand alone units - clip it to the dashboard and off you go. Anyway, advertisement over - it has, like most SatNavs, the ability to add your own voice, saying various phrases. There's about 30, I think - just get a .WAV file, rename it, put it in the right directory, and there you go. It would be a relatively simple matter to get clips from songs and do exactly this. For what it's worth, I think that every time you get in the car, you should hear a clip from The Headmaster Ritual of Moz saying "I wanna go home".