We had Nav in my wifes VW Touareg, it was terrible. None of the streets in my town were even on the system. Needless to say that vehicle is now GoNE!
We opted for the non-nav HCH. I have Nav in my Caddy and use it on and off.
I wonder if the Nav system in the HCH has more functions related to the vehicle systems that in the non Nav car. ie does it show average fuel used, economy and such.. like the toyota system.