Usefull hint
I searched very long because i want to use my nexus 7 in the car
Tasker: screen off - shell command 'reboot -p' as root
Screen timeout 15seconds
Developer settings: screen always on if power connected
Bootloader:
http://xdaforums.com/showpost.php?p=39633079&postcount=9
If ac connects (car starts and give AC) power on fully
Do not start in loading mode
Works with old (this) nexus 7
Give usb ac with an 3A lighter loader working with gps 'skobbler' and spotify
But i have flight mode on (spotify an skobbler are offline)
With activated network the charge is going lower then the loading