[zigurat]

When I enter a destination into the Navigation system of my 2008 E93 335i, it shows me the traffic along the way. However, the Estimated Time of Arrival ("ETA") on the display does not appear to factor in any traffic delays.

For the same route, (e.g. home to work), the Nav assumes the same amount of time for the trip, regardless if traffic is heavy or light. For example, it always estimates a travel time of approx. 15 minutes from my home to my work, even if I'm travelling in rush hour traffic, when the commute is more like 30 to 40 minutes.

It is my understanding that the ETA is updated based on traffic in the 2009+ Nav systems, but my question specifically pertains to the earlier Nav version.

[comebackidlci]

Not sure, but I would assume the ETA would adjust to your speed, which is slower in traffic

[persian54]

both my 335i and z4 adjusted due to my speed

[ChasVS]

The ETA is based on route and speed limits on those routes. While it does shows traffic, it has no way to factor how that traffic will affect your drive. It does, as others have mentioned, change the ETA based on your actual driving. Drive fast and it adjusts for sooner ETA, drive slow (or be slowed by traffic and Stop lights) it adjusts for later ETA.

[poiney]

Originally Posted by ChasVS

The ETA is based on route and speed limits on those routes. While it does shows traffic, it has no way to factor how that traffic will affect your drive. It does, as others have mentioned, change the ETA based on your actual driving. Drive fast and it adjusts for sooner ETA, drive slow (or be slowed by traffic and Stop lights) it adjusts for later ETA.

This is consistent with my experience.

Since NAVI has real time updates, you would think that for those specific routes it could give a realistic projection. However, then it might encourage always taking side streets which are also slowed down by traffic, but the NAVI doesn't know it.

[persian54]

It's kind of hard to determine the speed of traffic

I've been through 'yellow' parts where I'm doing a good 55-60 in one lane, while the lane next to me is going 40.
Then I slow down, then I speed up...
it'd be pretty hard for it to guess that prior to it occurring

but using your speed to adjust the ETA is simpler and much more doable

[2kaccordocoupe]

I think it's only based on distance and speed limits. We don't have the traffic option here in Canada and I find that the initial estimate for ETA is always much higher than the actual driving time. As you get going I think the car takes your average speed and evaluates that to determine ETA.

[Deltari09]

The iDrive ETA is based off of D/R, which is your Distance To Destination, as well as your Average Trip Speed. If your Averages change, so will the ETA.