A system having a user interface which presents map data Dmap. An analysis unit analyzes map data Dmap, determining a quality Q for these map data Dmap which are to be presented. The determination is based on whether the respective map data Dmap are available and/or reliable. The quality Q is presented graphically by a presentation unit. The risk of wrong decisions being taken on the basis of deficient map data Dmap is reduced considerably, since the user can easily decide whether there are reliable map data or not.