given a few evenings and enough will, you could probably make something pretty awesome with a raspberry pi or one of the other SoC boards out there.
integrating it with the dash might be a pain, you would want full touchscreen for normal use. sod using a USB keyboard to change radio channel!
edit: people are already on the case...
https://www.suprmasv.com/projects/83/raspberry-pi-carpc and
http://www.engineering-diy.blogspot....13-update.html