You might add a CarPC to a car; BMW uses the whole thing
BMW has just come out with their ConnectedDrive concept vehicle. This is intended to showcase how they think the car and its interface will be connected to the world in the future.
There is little information out on it so far... but I found some interesting tidbits at the following:
Bangkok post: A connected world
cnet: BMW Vision ConnectedDrive concept (photos)
The truth about cars: BMW’s Vision Of The Roadster Future
And more information on BMW and their ConnectedDrive systems are here.