Would make a GREAT DIY topic.

How do you turn the tablet off or on?

There is a App called Power Manager. Basically, it knows when the tablet is receiving power from the charger and automatically turns it on and disables sleep mode. Then when the car is turned off it automatically disables all connections and goes into sleep mode to conserve power.

Where do you get the app to show all of the gauges for the car? And does it have to be physically connected to the car in order to receive the info on it while driving?

It's called Torque on the App store and it connected through a Bluetooth OBD-II

Scan Tool

You need to remove the two screws holding the OBD port in place under the steering wheel and relocated it off to the side. Otherwise, the adapter will hang down and hit your leg. I guess with all this interest I'll have to do a DIY write up with pics.

Awesome youtube video. Exactly what i want to do with my car, but I need a headunit with bluetooth ad2p so I can stream audio from the tablet. Between that and having to gut the entire Bose system and throw down the cash for speakers, subs, a box, and amps... yeah. It's a small investment.

You could use a physical antenna adapter to override the fm input when in use. You would suffer from some quality loss though. Otherwise, the easiest most inexpensive way to do it is to get the adapter and wire harness that allows you to use one xm input for aux. As a bonus it would also let the stock bose deck control an ipod. It would only set you back about 100 bucks.

I like that a lot. I just can't see dropping 8 gs on a nav system and heated seats. Although, I'll try to find a used z with the touring package if it is a good deal.