Interesting question (to me at least ;-)
The more options you add to a vehicle, does it use the same CPU to process the information requirements?
Example, the sat nav surely uses some central computer, and other "things" on the car feed into the central display so must be processed somewhere along the line. By "other things" I mean what if you had adaptive lights that are constantly scanning for other cars in the distance. That takes some CPU right? Also, what if you also have active cruise control, more CPU required to keep going, lane change system etc...
1. they all have their own little black box processing power and just feed signals to the master display OR
2. they all use some central processing power and the more options you add the more it slows down (like my PC).
See where I'm going? Hope some person has an interesting response to solve my curiousity :-)