Inspired by this thread I went ahead and did the same thing with my nexus 7. One hiccup though. How do you turn the unit on? Did you wire up something to the power button inside the unit? Or did you use some sort of cheap mechanical solution to press the power button?
If you leave it on all the time it will eventually drain your car battery right?
For those interested. I use the same hyco bar solution (its found in the plumbing section of home depot btw. 87 cents. (you only need 1 bar).
Instead of plank of wood i used a piece of rubber drawer lining which is between the nexus and the hyco bars. and provides it from slipping around or damaging the back of the nexus if i ever want to remove it.
Just can't figure out how to turn the nexus on. Is there a "power on when plugged in" setting in cyanogen mod perhaps?