[ltcal94]

The easiest way is to ask them (specifically) if it has buttons labled INFO , TELE, and AUX. If so, it is the CD based system (INFO-RADIO-CD-TELE-AUX-NAVI-MAP and ESC).
The DVD based system will have the buttons labled as follows:
VOICE - RADIO - CD - MUTE - DEST - NAV - MAP and BACK.

Lastly, it looks like they started with DVD , then made some more CD based systems because the software was not available and then finished with some more DVD systems. I just bought an '05 with the CD system and was researching the vehicle hoping it actually had the DVD system (my JETTA has it) . After playing with it , I am ok with it.

Hope this helps.

 

[ltcal94]

Funny you should asked as I had the same question myself, particularly since I am spoiked by the DVD based NAV on my JETTA. I called NAVTEQ and they explained that all the CDs have a built in US major roads , I think he called it cross country USA or something similar. So in the example I asked about, I would show a major destination, such as Miami, from my origin. It will then plot the course, once you are in the region you stick in the correct CD for the region and you can enter a specific address in Miami. I am not sure if you could do this the other way around and I have yet to try this myself, but I can definelty understand the logic.