Do you do a lot of gaming while driving? I don't see the purpose of an Xbox in the car as it's hard to have 2 hands on the controller and on the wheel at the same time. Unless you plan to integrate the buttons from the controller into the steering wheel... hmm... but then there's still the "eyes on the road" issue.
Regardless, the hardware seems like it would check out. Make sure you check the wattage drawn by the Xbox. I remember it being pretty high compared to a PC.