If you don't want to play around with mounting screws there are
arms that will mount in the cup holder such as this:
So, that is a way to use your iPad as a navigation device.
I also hooked up with a guy that started a kickstarter project to mount
iPads in the CD player of the car:
I am happy to see that he is now selling the kit on Amazon. Only thing is, for my
next trip, I need the CD player.
I am going to be driving to Canada. I hear that none of the three big map programs
(Waze, Google, Apple Maps) offer offline mapping. So, even with the cellular GPS
chip I may out of luck once I enter Canada.