Love the Nav system in the 2006 GXP, but it did piss me off a little to find that it did not play MP3 discs, but played CDs only. The Nav DVD is definitely fully "hooked into" the heads-up display, showing how long to next turn, which way, the name of the street, a decreasing countdown in tenths of a mile, and a graphic "percentage to completion" bar that works in reverse to show how much distance you have remaining before the next turn. The HUD is EVER-SO-MUCH better than my previous Grand Prix GTP...much more robust, clearer, and chock full of other non-Nav information, as well (compass direction, MPH, radio station name from the XML satellite radio, etc.) If the information you need to know is too much to display on the HUD, it will refer you to the in-car display screen for additional information.
Definitely one of the best add-on toys and improvements in this model.