Estimated time of arrival (ETA)

Mine is generally fairly accurate. It's just a function of computing speed and distance to travel. Of course, it's out the window if you run into a traffic jam. It does not seem to update very quickly at that point.

My 660 is quite accurate at eta as well as when it tell's me when and where to turn. Sometimes it may be off a few feet when making a turn.

My 750 is pretty much on the mark with the ETA, even if I'm in traffic. It resets the new ETA quick.

There is currently a discussion going on over at the www.zumoforums.com about the ETA of the Garmin Zumo. It appears that the ETA predicted for British users over in Europe can be extremely inaccurate. Apparently users in the US do not experience such thing.

For a trip without traffic, especially a long one, it has been accurate.

I drove into work in Washington, DC, the other day, and--probably due to the number of lights and some traffic along the way--it was not very accurate. It expected me to get home in about 20 or 25 minutes, but it took about 40 minutes, which is the norm.

I have been most amazed with the accuracy on long trips - over 500 miles. It is usually within 15 minutes (not counting the time I stop for eating or gas).

In town driving it does not seem to know which corners have stop signs or lights - and if you get stuck on a slow red it can affect the time. I think that they could increase the ETA time about 3 minutes or so for most of my in town driving and be ok. Still pleased though as it help to let customers know when to expect me...

Daniel

use my hand held for everything and it adjusts ETA fairly quickly and has never been off by more than a few minutes.

never had a problem with my streetpilot C340 or the new Nuvi 350
Both are mostly accurate unless there's crazy traffic jams

I think what Mark is implying is that the INITIAL ETA tends to be rather accurate. Of course the end number will be accurate since it adjusts as you go, but I too have noticed that if the Garmin initially (when I first start) says I will be there at 7:18, then I am usually there at about 7:18.

The thing I find odd is that I am a pretty fast driver (70-75 MPH on a 55 highway) and I still arrive at about the time initially quoted. So it makes me wonder. If I drive fast and make it, does this mean most people end up being later than the ETA if they tend to stick to 60-65 MPH on the highway?

PT

I know my ETA (nuvi 350) is prettry accurate, once I get going. Initially, to calculates the ETA, then after I start my trip makes some slight adjustments.

Which begs a question - If I understand it correctly, TomTom will now be using historic traffic information to calcuate routes (and I would guess, ETAs too). Based upon the day, and time of day, TomToms will adjust your route to avoid heavily trafficed roads. I think they said "Better 50% of the time" (which led to my question - "is it worse the other 50%, or just the same?).

Anyway - anyone with a TomTom and the new route calculator care to chime in?

My Nuvi 660 updates pretty darn quick! Even if I'm stuck in traffic I can watch as the ETA slowly gets longer and longer! Just another reminder of HOW LATE I'm gonna be when I finally do get there! (LOL)

My 2720 (Emily) is very accurate in ETA - I always check it as soon as I start and check it when I arrive. Unless unexpected traffic happens - but then, I don't see how that could ever be calculated.

How would you know, before you leave, that 5 min after leaving home some idiot wrecks and traffic comes to a stop?

It's all in the formula....

Each class of road has an 'expected average speed' - and it calculates the speed limits, average speeds and guesstimates an arrival time from the start, and constantly adjusts it based on your driving habits.

My Nuvi 660 is usually on the money. It adjusts for things like stops and/or traffic quickly. I'm satisfied with the results and adjustments.

Mine is pretty accurate when you take into consideration traffic light traffic and other variables that can't be programed.

It's almost too accurate. It's quite remarkable!

I agree with the above, my ETA is very accurate. When I take long trips, it is more accurate on highways more so then a short trip through the city with traffic and stop lights.

Mine is surprisingly accurate. It updates well when I'm driving slower that it anticipates for the road type, or if I'm stopped. On my 2200 mile trip to Florida in January, it was spot on for each full day's drive, only updating when we stopped for lunch and gas, and the updates were accurate.

I find the ETA is usually more dependent on me than anything else. It's a calculated # assuming you drive the speed limits and don't run into any unforeseen traffic (unless you have the traffic service). I always add a few minutes (5-10%) to account for lights, traffic, misc.

I have been impressed with the accuracy. I took a several hundered mile trip last weekend, when the traffic on the Interstate sped up (from 70 to around 80) the unit recalculated ETA to reflect the higher speeds. Was good within 5 mins.

I encountered the same thing. My nuvi told me I would arrive at 1:30. Since I was driving 20kph over the limit, I figured I would arrive well before then. But, sure enough, I arrived at my destination within minutes of the ETA. I was pretty impressed.

garmin350 ETA is very accurate. When in traffic, the ETA time adds more time on and subtracts when we start moving. ETA also chspeeds up when I drive faster or slower. Works for me.

On several occassions I have had to take short trips to unfamilar places. Question was - how much time do I allow to make the trip and not get there too early or late? My GPS has been accurate - actually accurate enough to scare me. Reason I posted the question was that I didn't know if the few times I relied on Jill (my GPS) was a fluke or not, being so accurate. Seeing all these positve replies gives me renewed confidence in Jill agian. Thanks again for all the replies.

My C340 (Emily) has proven to be very accurate in ETA; she also adjusts quickly to long sits at stoplights or traffic, or those occasions where I get a lead foot. That's gotten to be one of my very favorite features on the GPS: even when I know exactly where I'm going, I can tell whether I'm on time or late, or whether I have time to stop for coffee, and can call where I'm going if I'm going to be late, and give them a pretty good estimate of when I'll be there.

My wife took a 7 hour trip (according to Nuvi 350), after two 30min stops, it took exactly 7 hours

I have used a friend's C340 and my C550 several times now and have found the ETA's to be very accurate and, in fact, updates en route. So far I think I have met my ETA every time.

I have noticed that when I am sitting at a traffic light my Nuvi 650 will add minutes to the ETA.
JeffSh

Dear Jeff,

My 650 does the same thing. On the way to work in the morning, the ETA will underrate the twenty-minute ride by six or seven minutes at the beginning and slowly adjust along the way. The morning commute is the quick one; coming home takes five or ten minutes longer.

david

The unit knows the speed limit on the roads you will be traveling to do the initial computation then it adjust based on actual speed.

This can be better observed if you do a simulation that goes over city streets and highways, after the simulation starts go to the info screen and you will see the speed increase or decrease based on the road the simulation is on.

I don't think that is true. The maps are not so detailed to have speed limits for all roads. At best it probably estimates average speeds over types (e.g. highway vs. city vs. rural, etc.) of roads.

PT

The database classifies the roads into different segments (interstates, major highways, residential, etc.). Then the routing algorithm uses the average expected speed on the class of road in the calculation.

That is what I meant to say, "type of roads" but you can see the change when running simulation.

I find the ETA pretty good on my C530. It even updates along the route. Generally though, it always appears more optimistic (earlier ETA) at the outset than what actually happens.

For long trips, mine is always optimistic. It does not take in account the Human hunger factor or the Car Needs Fuel factor.
*smile*

I have found that mine can be rather pesimistic sometimes. I thought something was wrong with my Nuvi 760 because the ETA was always way off. --- That is until I realized that my GPSr was in Pedestrian mode
It is rather humerous to watch the ETA adjust as one heads down the road...