I saw a video fairly recently on the pitfalls of new cars, the "infotainment" system being one of them. One may as well be learning a whole new operating system when dealing with those things, I don't think anything about them is standardized.
I recall riding in someone's late-model piece of crap and wondering "where's the bloody ignition key?" The owner uses a USB stick with the stereo and brags about how many songs it can hold. Mom seemed impressed by it but I was thinking something like "Yeah, so?"
I just modded an AM-FM-8 track car stereo for use as my computer's sound system, sounds pretty good too.
I didn't want to permanently modify the stereo's case so I gutted and cut down a bad VHF tuner; I thought it ideal as it already had RCA jacks and the hole in the back fit perfectly over the volume control shaft. A micro-mini DPDT switch fit nicely between the stereo's case and the attachment. As for power I just tapped the 12V rail in my computer.