Right, but it can't use the current speed, it has to use some sort of average or every time you are in stop and go traffic, the ETA would "roller coaster" up and down rapidly. The average speed allows for smoother, more gradual ETA adjustments...

 

If you watch the ETA you will sdee that it indeed goes up and down, but not that fast, because it has the predefined speeds you drive on this kind of road.

Let's say, you're driving on a highway, the predefinition is 130 Km/h (I have forgotten the real speed, just an example here), you get an ETA for the distance you have to drive this road (if your destination is at the end of this road, for this example). The ETA you get before you start driving off. While you drive, the computer calculates new. If you then only drive 100 Km/h, the time will be corrected and the ETA goes up. But because the difference is 30 Km/h it is not like a rollercoaster. But you can see the adjustment. It happens all the time! If you drive 200 Km/h your ETA will be corrected also. Then it will be very drastic.
The computer is not calculating with your average. The problem is, it calculates with those predefined speeds. And if the guys at navteq have marked the road as an highway, but it isn't, your ETA and all the routes you get are messed up.

 

...but the fast route is slower than the short route (not in real driving, but in estimated driving time shown by the NAV)???

 

New car is fine. Only had the steering wheel sensor problem so far and several creaks and rattles. But if I want a quiet (...and boring...) car, I can drive my wife's Subaru.....
I am soooooo much happer with the manual (sorry, Rudy).
Btw., I recently drove a Audi DSG in Germany, no that is a gearbox I would buy right away - but that would mean buying and Audi and I am not 60 yet......

 

Now two things come to my mind:

First, if that happens when the car is still not moving, it could be an error, or it'sd just temporary, until a better/the best route is found.

Second, it happens while you drive, then there is a difference in between the speed calculated by tha nav for the roads you use, and the real speed you use.

Anyways, it's somehow strange to see, I agree.

 

Iceman, it sounds like you know what you're talking about, but I can say this for sure -- If I go well above the 'normal' highway speed limit for long enough, the Nav will adjust my ETA to a time that assumes that I continue to exceed the speed limit. Example: I have 45 mis. remaining, and it says I'll arrive in 30 minutes = 90mph. Therefore, as Rudy suggested, it must somehow take my recent speed into account in calculating the ETA, not just the predefined speed limit for the remainder of my trip.

Of course it could simply be an data error on the Nav DVD with the predefined highway speed !!

Thanks.

 

The "average speed" is the average speed the car has done over the last 30 miles (or so I have read). It makes sense that the ETA is then adjusted when there is a difference between that average speed and the expected speed assigned for that particular road.

Generally, I am impressed by the accuracy of those ETAs.

 

Yep, of course. The recent speed, but not an average of the sppeds you were driving somewhen before. On this road you'r eon right now, you're driving faster than predefined speed is, so your current speed will be taken into consideration for the calculation on the ETA, for this road. On this road it's obvious that you can drive faster, and do. But once you drop much below the predefined, it adjusts itself back, so it works both ways, and therefore can't be the average speeds you were driving.