A method performed by a positioning system of a vehicle is disclosed for determining a position of the vehicle along a road including one or several road markings arranged on a surface of the road. The positioning system detects road markings, matches detected road markings with mapped road markings of stored map data based on comparing characteristics of the detected road markings with mapped characteristics of the mapped road markings. The positioning system furthermore identifies a mapped identified road marking determined to correspond with a detected identified road marking, and determines a positioning estimate of the vehicle along the road based on a mapped road marking position associated with the mapped identified road marking. A positioning system, a vehicle including such a positioning system, and a mapping unit and a mapping method performed therein for creating map data to be utilized by the above mentioned positioning system are also disclosed.