The described navigation system makes use of the attribute pertaining to the existence of “preferred directions,” in particular, inside multi-story car parks. These preferred directions are not limited to a plane or to an orientation. Preferred directions are, in particular, longer entry and exit paths. The method detects a departure from the digitized area and then determines a preferred direction that is defined as a principle axis or a principle axis direction. When traveling within the non-digitized area, e.g. of a multi-story car park, the system monitors whether the vehicle moves within a predetermined limit of the previously defined principle axis direction. If this is the case, it is determined whether a deviation exists and this deviation is optionally corrected to conform with the principle axis direction. This enables compensation of errors that are caused, in particular, by the direction detection.