Car PC is not a hard thing to build.
I built one and its running XP OS with motorised 7" screen.
Built in Rodio, TV, Cameras input, Ext Audio in and a build in 25Wx4 power amp.
On top of these, GPS, play MP3 & Movie, internet broadband, touch screen, bluetooth, wifi..... oh karaoke for sure.
It is more than an inflight entertainment system.
Of course very costly...!