I have a 2012 Nexus 7 with a bad screen waiting to be repaired to go into mine. Need the rest of the supporting gear first though. (4 channel amp, OTG cable, USB DAC, other things that I'm not thinking of).
Somebody posted about their build in another thread, and if you go to Youtube and look for Mighty Car Mods, those Aussies installed an iPad in a Subaru Legacy. It's all a similar process though.
A lot of the power issues can be solved, if you have an Android tablet, with 'Tasker'. You can set it so if it detects that it isn't being charged, then it goes to sleep. But you need to connect your charger to switched power, and it sounds like Matt was going through the cigarette lighter, which - in 06s at least - stay live when the car's off. The other good thing is perfection, with the newer Dash, it may be hard to get it perfect. If you have an 05-09, it looks much more like it should be there.