Added thought, the Owner's Manual and the Navigation Manual that came with my car both list the specific iDevices that are supported (i.e. tested) by the manufacturer. I have seen people complaining that a certain iDevice doesn't work and it's usually not listed in the book(s). Don't know what your books say, but it's worth checking.
I plugged an old iPod touch into the USB port in my car and was surprised to see the iPod's screens come up on the Navi screen and the iPod was showing the Honda logo that displays on the car screens when you start the car.