setting route preferences inside each planned trip

[danham]

@jfheath, you mentioned the XT may learn something from the way it is used. Can you expand? It doesn't seem that smart to me.

Not really, I'm afraid. Not the way it is used, but the roads that you ride. I have read that it does it. I have observed that if I travel at 50mph on a 60mph road, it will adjust my ETA - seemingly as though it assumes that I will travel at 50mph on 60mph roads all the way to my destination. I have also formed an impression that it learns how fast I ride on particular class of roads. SO that it can better estimate my time of arrival in the future.
But I have zero evidence for this.

Some years ago, in a long-since discontinued Garmin forum, I corresponded privately with a Garmin software engineer (who was under an NDA). At the time Garmin would occasionally send me a GPS to road test and review (no, I was not allowed to keep them). He verified that some of the high end Garmins did in fact compare your customary driving speed to what the road was classified for (not necessarily the posted limit) and would use that "learned" information to calculate ETA.

A simple test of this is to do a full reset to factory defaults and see what happens to ETAs on routes you use a lot. If your usual speed is higher than the GPS's default values (probably road classification), the ETA shown after the reset will be later, until it "learns" your habits. Another bit of supporting evidence is that over time it takes driving faster and faster to "beat" your usual ETA on a regular route that you travel often.

-dan

[tombarrington]

I have observed that if I travel at 50mph on a 60mph road, it will adjust my ETA - seemingly as though it assumes that I will travel at 50mph on 60mph roads all the way to my destination.

This makes sense to me. I think my BMW does the same thing with fuel Range-to-Empty using some average consumption.

He verified that some of the high end Garmins did in fact compare your customary driving speed to what the road was classified for (not necessarily the posted limit) and would use that "learned" information to calculate ETA.

Seems like this could be sold as a feature rather than leaving everyone scratching their heads.

[danham]

He verified that some of the high end Garmins did in fact compare your customary driving speed to what the road was classified for (not necessarily the posted limit) and would use that "learned" information to calculate ETA.

Seems like this could be sold as a feature rather than leaving everyone scratching their heads.

I can only guess, but wonder if Garmin is worried about people not understanding how road classification and speed limits work in the GPS and "racing" against the GPS to try to beat the previous ETA. It's bad enough that some idiots have tried to sue when they blindly followed a GPS off a cliff.

(Road classification is a measurement of what the carrying capacity of the road is, what volume of traffic and speeds it was designed to accommodate. Authorities can use this to set speed limits, or can set limits based on various other factors they choose.)

-dan