I came from Luisenstraße (orange), moving southbound in order to turn into Detmolder Straße (red) using the roundabout. However, Navigator suggested to leave Luisentraße earlier, drive through the parking aisles (!) and then turn into Detmolder Straße. That's nonsense.
What's the reason? Parking aisles (as all service roads) should never be considered unless absolutely necessary.
I got it. The profile settings that makes the difference is "Small Local Road" (German: Gemeindestraße). Once it is active, the parking lot will be considered. That's still nonsense, as service roads are something different than that.
By testing that, I discovered another issue: For this test, I have set up two Routing Points. When I would switch to Itinerary, I would "Calculate route" to see whether the parking lot is used or not. On tab Route setup, I am able to change "Road Restrictions" without the need to select another vehicle profile. But: the new restrictions will be considered only for "Calculate route", if you re-validate the "Routing Mode" (that is: to tap onto it and to select it agian). If I don't re-select the current routing mode, "Calculate route" would not detect any changes and thus would not suggest you a new route, but only repeating the last one. No problem, if I select another vehicle profile. The problem only exists when changing the "Road Restrictions" only.
Well, it is hard ;-). Navigator 12 does not have enough road categories, so it is difficult to "tune it" for "universally reasonable" routing. While "Other Roads" should be almost always disabled (for Car), "Small Local Road" are sometimes necessary. Navigator 14 has more bits for speed resolution, so what we could do is keep "service road" still under "Small Local Road" category, but lower the "default speed" ... Martin