Interesting concept - have wondered when we were going to see this technology in the car. We've had smartphones and Sirius receivers that can pause and rewind, so figured by now we'd already have a smartphone/tablet type device that would replace our existing head units.
I stumbled across this head unit: http://www.alibaba.com/product-gs/48...d_Car_DVD.html
Also ran across this thread of installing a tablet in a Jeep: http://forum.xda-developers.com/show....php?t=1372396
This thread has videos of an iPad install in a Toyota: http://www.tacomaworld.com/forum/aud...-wrangler.html