Different in-car navigation map displays have been tested with 60 drivers in real driving situation.The independant variables took into account 3 variables of guidance information (map alone / map associated with auditive guidance information / map associated with written guidance information), 2 variables of itinerary complexity (number of turns), 2 variables of information complexity (number of symbols). The dependent variables were composed of visual explorations, the memory recalling performance, the preference of map designs, the steering-wheel movements, the speed variations of driving.The results have shown up that map presentation associated with written directions resulted in a majority of the drivers being able to recall the route to follow. The complexity of map display designs had significant effects on the number and the duration of visual explorations and memorization performances. In the case of subjective preferences, most drivers preferred the simple map display design. Moreover, it was found that the drivers reduced the speed of their vehicles while consulting the map displays. In conclusion, it was possible to propose some recommandations concerning the designs of navigational map on board vehicles.