Nice write up, I like the apps the author mentions (NavFree USA, CarHome Ultra, and PowerAmp). I don’t think I would get PowerAmp, maybe not CarHome too. But I like NavFree in general since it does maps without a cell signal needed. Only thing I wish was added bluetooth as a host so a phone could stream to it.
http://www.instructables.com/id/Android-tablet-as-carputerstereo/