Method for updating an electronic map, comprising the steps: - detecting first objects (2a, 2b, 2c, 2d) which comprise a respective reference direction for a second object (4, 4a, 4b, 4c, 4d) and a respective distance specification, by means of a respective sensor device by one or more motor vehicles and assigning a position (3a, 3b, 3c, 3d) of the respective motor vehicle detected by means of a position detection device of the respective motor vehicle to the detected first object (2a, 2b, 2c, 2d); - producing respective first object datasets, which represent the respective detected first object (2a, 2b, 2c, 2d) and the position (3a, 3b, 3c, 3d) assigned to the respective first object (2a, 2b, 2c, 2d), by means of an evaluation device of the respective motor vehicle; - deriving from the first object datasets a second object dataset which represents the second object (4, 4a, 4b, 4c, 4d) external to the vehicle different from the detected first objects (2a, 2b, 2c, 2d); - updating the electronic map by adding map data corresponding to the second object dataset to the map by means of a computer device, wherein: - the second object dataset represents at least one property of the second object (4, 4a, 4b, 4c, 4d) which is not detected directly by the respective motor vehicle, and - the second object (4, 4a, 4b, 4c, 4d) is a landmark and - during the update as map data the not yet saved landmark is added to the electronic map, wherein determining a position of the landmark on the electric map comprises trilateration, taking into consideration the positions (3a, 3b, 3c, 3d), reference directions and distance specifications assigned to the first objects (2a, 2b, 2c, 2d). - detecting first objects (2a, 2b, 2c, 2d) which comprise a respective reference direction for a second object (4, 4a, 4b, 4c, 4d) and a respective distance specification, by means of a respective sensor device by one or more motor vehicles and assigning a position (3a, 3b, 3c, 3d) of the respective motor vehicle detected by means of a position detection device of the respective motor vehicle to the detected first object (2a, 2b, 2c, 2d); - producing respective first object datasets, which represent the respective detected first object (2a, 2b, 2c, 2d) and the position (3a, 3b, 3c, 3d) assigned to the respective first object (2a, 2b, 2c, 2d), by means of an evaluation device of the respective motor vehicle; - deriving from the first object datasets a second object dataset which represents the second object (4, 4a, 4b, 4c, 4d) external to the vehicle different from the detected first objects (2a, 2b, 2c, 2d); - updating the electronic map by adding map data corresponding to the second object dataset to the map by means of a computer device, - the second object dataset represents at least one property of the second object (4, 4a, 4b, 4c, 4d) which is not detected directly by the respective motor vehicle, and - the second object (4, 4a, 4b, 4c, 4d) is a landmark and - during the update as map data the not yet saved landmark is added to the electronic map, wherein determining a position of the landmark on the electric map comprises trilateration, taking into consideration the positions (3a, 3b, 3c, 3d), reference directions and distance specifications assigned to the first objects (2a, 2b, 2c, 2d).