Weird Nav behaviour

[senwar]

I've been travelling with work recently, and every time I drive back from Norwich to Sheffield and go over a particular roundabout, the navigation directions change and a new route is calculated.

I'm following the route as per the nav, even the display looks right, but it goes from 141 miles to 188 and takes me completely off course (obviously I don't follow it).

Any ideas what is causing this to happen?

 

[EdButler]

You may have the "Use Motorway" option turned on... When i had this, it would do whatever it could, reasonable or not, to get me on the motorway.

Mine tried to take me from Duxford - Sheffield via the M25!!! Just because there was a higher percentage of motorway at a guess. Switched it onto "Fast" route and its a little better.

When i was convoying the Sheffield lot down to Midlands Breakafast club, it predicted 20 miles and 1 hour more than it actually took as it was predicting a terrible cross country route (we took that on the way home though! ). My opinion is as always with GPS Nav systems: Always have a reasonable idea of where youre going beforehand!!