I recently drove a (non-volvo) rental vehicle in the UK and used its integrated navigation system (i.e. from the manufacturer, not one of those add-on GPS unit rental companies sometimes provide as an option). At one point, it thought I was driving on a surface road somewhat parallel to the motorway (similar to highway in the US, I suppose). It kept on suggesting ways to re-enter the motorway, but when the map suggests that the surface road came to an end, the vehicle icon on the map got stuck on an intersection and got farther and farther away from my current position.
I suppose navigation systems aren't always correct, either it hasn't reconciled sufficient location precision or there is some discrepancy in the map database (including perceived traffic condition).
Yeah, the alternative route is kind of BS. Going an alternate route with a million twist and turns to save three minutes isn't worth much. And is the real-time traffic data it's apparently getting on side roads used in the alternate route as sufficient as the main road?
Also, I do wish the alternate route was visible on the main touch display -- that way I can better evaluate the alternate. It's tough sometimes to tell sometimes looking at the mini-display between the speedometer and the tachometer.