I have just downloaded a few POI files to my Nuvi 255 W
software version 4.40,
Audio version 2.20,
GPS software version 2.38b
In the list of POI a distance in km is indicated, I assume the distance from my current position. My geographical awareness tells me that these distances seem to be too small.
I select one of the POI, show it on the map and then press "back".
Now a tab with route info slides into view: the distance displayed here differs from the one in the POI list. The larger distance displayed in the tab seems to make more sense.
I have checked if the difference might be a conversion hickup from km to miles, but the factor between both distances is not equal for all POI.
I guess calculating a route for each of the (many) enties on the POI list is not feasible, while doing some relatively simple maths on sets of GPS coordinates is.
I had not expected this to be the explanation and I am suprised by the large differences between the crows flight and calculated route distances - upto a factor 1.8 for some destinations I checked.
Anyway, I now know how to interpret and use the data. I guess the cases where you make a POI selection based on the shortest straight line distance - only to find out that this selection does not render the shortest route - will be rare.
What I usually do is to select the closest poi and press the go to button. this will then calculate a route to that location, and give a more accurate distance. You could then select the next closest poi and check the recalculated route to that location. For very short distances, you probably wont save much, but for locations that are some distance away, it can make a conciderable distance ajustment.