Why don't you mod, lets say, the IR remote into, say, the steering wheel so that you can move through menus and press stop and play, etc using buttons modded into your wheel (or dash if you don't want it that way) like a normal radio, and have another controller in case you want to play games (when you're not driving, of course!

). I've been thinking about this topic for some time (coming up with the money and the time and resources to mod my Scion xA has prevented me from going forward on the project) and that seems like the best option. You could even use XBMC instead of a linux solution! The touch screen would be nice, no doubt, but unless you opt to use linux and find a usb touch screen with linux drivers, you're pretty left with using your creativity and finding some other solution.