Out of the box, any high-end android phone can mirror its display on a DVI or HDMI, connect to a keyboard, mouse, HDD, OBDII, or many other USB/BT peripherals. There's no modding or hacking needed, it just works.
90% of a basic carputer is already present on the phone, all that is needed is support for an absolute-posistioned USB touchscreen. It might work automatically, I don't have one to test.
Imagine a tablet-integration build with no worries about wifi, synchronization, paying for mobile broadband, having to still pull out the phone for making calls, etc.
I think it would be really cool.