I have recently added a 7" Tab to my car. It does not replace the head unit, but works in conjunction with it. I have not found a favorite audio app yet, but am currently using Winamp. I also use TXTab to receive text messages from my phone on the tablet. Still working on the best configuration, but seems to be working pretty well so far. I use Waze for gps guidance, it is pretty slick and has user generated traffic and police info. I have Tasker automate several things like starting the music and traffic apps when the tablet is in car mode and has power. I use Car Widget to organize my most used apps, it has a nice large button interface.