OldGnome wrote:However, my understanding of the data used by Garmin is that it is "informational" and "used for calculating trip times."
That doesn't give me a lot of confidence in the accuracy of the data. I have, in fact, found a few locations where we lived in WI where the data is quite inaccurate.
Every GPS I owned between 1998 and now offered this so-much-wanted speedalert. With fresh mapdata I would get irrelevant warnings some of the time; before the maps where 2 years old I would get false positives (and false negatives, but you don't hear those) all of the time. This type of data is very volatile and changing all of the time.