Estimated driving time 2495 vs 2597

Your 2495 has adjusted the estimates, based on your driving style. The 2597 will learn your style also, and after several weeks, its estimates will be similar to your 2495.

I don't either of the units so I'm just guessing here. If both have the "My Trends" feature, perhaps one is active and the other is not.

I agree with CraigW that the cause is likely the average speed by road type learning that is causing this. Garmin confirmed several years ago that the nuvi line adjusts driving time and simulation speeds by road type based on your driving history. If it was MyTrends or TrafficTrends causing it, I think you would get different routes on each unit.

You could prove this if you want to make the effort. Do a hard reset on both units (make sure to back up your Favorites first). Then before you have used them on the road, recalculate the routes and compare the estimated driving times. A hard reset will reset the speeds by road type back to the default values and force the unit to relearn.

Hi

Thank you for the quick response! Both units have gone through a hard reset, the difference in the estimated driving times still remain. The 2597 is my third Garmin unit and I have always been impressed by the estimated driving times (when not stuck in traffic of course) but with my new 2597 I feel it is a step down. When calculating longer routes the differences are not as big (related to the total driving time) so I guess that the issue is related to estimating driving times in residential areas. Maybe the cost estimation of left/right turns or traffic lights etc are different between these two units.

The difference I have previously described is when comparing routes one the different units using the Trip Planer. When doing a direct "where to" navigation the driving time estimates are the same on both units.
The interesting thing is that the Trip planer on my 2597 has a different estimated driving time as compared to a direct "where to" navigation on the the same unit. Is anyone else experiencing different driving times when using the trip planer vs going to the same waypoint using the "Where to" menu? The difference is thus not between my two units but between using Trip planer and "Where to" which is even more confusing :-0

I haven't directly compared my NUVI2555LMT to a second GPS, but my 2555 calculated travel time at 1 Hr 20 minutes on a trip I knew should take about 15 less than that.

I watched the ETA on the dashboard and I drove through a couple of small hamlets and saw the ETA drop by about 5 or 6 minutes after. The drive through these locations only took me a minute or two at most.

It makes me wonder if the GPS has either an incredibly low speed figured for this location, or is calculating the size of the hamlet as much larger than it really is.

My old 350 seemed to calculate much more accurately. However, on most trips, the 2555 seems fairly close.

Go figger!

I had also used trip planner on the route where this occurred. Maybe the issue is with Trip Planner.

I use a 3790LMT. I made a few trips home to Sandia Heights, Albuquerque from a rehearsal location in Santa Fe over a period of weeks. At some point I noticed clear evidence that depending on just how the travel home over the dominant Interstate section was initiated, it had at least two distinct rates of advance it would use for ETA estimation. This is the same stretch of I-25 southbound from Santa Fe to Albuquerque, and there is not a plausible alternate route along that stretch.

Since in no case did I use Trip Planner, that was not part of this. I have not characterized initial condition differences, but they would largely have been which exact surface road I started back on and just where I was at the moment the calculation was done.

The difference was not tiny, either--something like 5 minutes for about 45 miles of Interstate travel.

I think some of the learning is by class of road, but some of the learning is by specific section of specific road. Not sure, but seems to match various elements of my overall experience. Possibly some of our observations relate to use of one versus use of the other.

I travel around town in Albuquerque with GPS on nearly all the time--and usually giving directions. It seems to me that my within-town ETA estimates are now far better with this unit than with any other GPS I have owned. My wife's unit (some model, firmware, and map, but different "experience") gives different ETAs). So in my case, around this town at least, I think the learning has been a positive feature.

I have seen two different units with the same exact setting can route from point A to Point B via a different route. One idea is that the new units may have more roadways that have speed limits assigned to them.

The thing is that when using Trip Planer to get a route from A to B the estimated driving time changes as soon as I activate the route. So without any real driving going on, the driving time from the Trip Planer is different from the driving time estimated as soon as I activate the route.

The same "problem" happens if I choose a POI and from the POI interface and from the POI page choose to view different routes (up to three alternate routes are calculated). The ETA shown on the different routes changes as soon as I activate my prefered route (still with no real driving involved) The ETA on the route drops from 25 min in the alternate routes overview page to 20 min as soon as the route is chosen. This behavior is only present on my 2597 device but not on my 2495.

I never use trip planner. Whenever going on long trip, I just save all locations and then select them from point to point. It always works well.

Works for me as well.

When I fly off to a visit, in, for example, the SF Bay Area, I check my likely destinations by trying to look them up on the GPSr. If I find them, the act of having done so puts them on the recently used list of my 3790LMT, and only for ones I don't find do I create a waypoint--which also gets on the recently used list.

So most places I want to go on the visit I just get off the recently used list. Calculation is fast, as are recalculations. My main use for the trip planning function is to "nudge" the routing by forcing one or more intermediate waypoints. Even in that case, I may just choose to navigate to the intermediates, without ever composing them into a route.