(– by Drizit #6240 –)
the Nuvi is their road going based gps, I have yet to find a "show on map" option for it. I suspect it may not be there otherwise why bother with the more expensive, smaller, non touch screened "offroad/hiking" gps's I suspect the real difference is the artificial limitations imposed by the manufacture. Also every gps manufacture and even different models will act differently. A GPX file is just a standardized list of way points to make the track. Google is your best bet for exactly how to do things with your GPS. I've been playing with mine on and off for a week or so now and have spent probably a total of 2 or 3 hours learning how to get to the point i'm at. It's not too involved.