NAV Time and Distance Display

I just got back from Mexico, and during the slow parts (accidents, traffic) the NAV automatically adjusted the arrival time. I lost 30 minutes outside Austin...grrr.

 

I belive the first time/distance you see when you first input your destination is set according to the speed that is for default in the nav options. you can modify these settings, like hwy speed and rural speed and the eta/distance will adjust accordingly to those settings.. i dont know if this made sense.. i lost myself in what i wrote.

 

Distance doesn't matter what your current speed is. It uses your current position and your chosen route to calculate the distance and that updates ffrequently enough that any time the car has moved any reasonable distance it is reflected in the displayed distance remaining.

Time is calculated by the distance driven on each of 3 types of roads times the configured speed for that type of road. In the NAV setting you can choose a designated speed for residential, non-residential, and expressway. The NAV assumes these speeds for any distance remaining on your route.

Using your instantaneous speed wouldn't work very well. Every time you stop the car, your remaining time en route would jump to eternity. Using your average speed for the trip so far, would be slightly better, but since the past is a rather poor indication of the future when it comes to traffic and travel times, it wouldn't be much better. It certainly would be nice if there was some way to hit a "traffic incident" button and have it use an alternate set speed settings.