The point that kev was trying to make....which may be very hard for those of you not familiar with a good carPC design is on the UI's usability when moving. No one is arguing that android doesn't have a great looking UI, we are arguing that it is designed to be used by a user who can afford to keep their eyes and a hand on the screen.
The completely separate application framework of android will make it impossible for a fully integrated solution (you would need to design a single carPC application containing everything). Things like changing songs, dealing with SMS notifications, making/taking calls while navigating, etc. require your full attention when using the android platform.
I have a droid eris as my personal phone and a moto droid for dev work and its an incredible platform. That said its important to remember what the platform was designed to do and how those design goals limit its functionality for other applications.

