Method for improving global positioning performance of a first road vehicle (10), the method comprising, by means of a data server (3, 4, 4″): acquiring data from onboard sensors (2a, 2b, 2c, 2d, 2e, 2f, 2g) arranged on the first road vehicle (10) and on at least two neighbouring road vehicles (10′, 10″, 10′″), the data comprising data on relative positions and data on heading angle and velocity of the road vehicles (10, 10′, 10″, 10′″), and acquiring global positioning data of at least two of the road vehicles (10, 10′, 10″, 10′″), processing (102) data comprising the global positioning data, the data, with corresponding timestamp, acquired from the onboard sensors (2a, 2b, 2c, 2d, 2e, 2f, 2g), and a motion model for each of the first road vehicle (10) and the at least two neighbouring road vehicles (10′, 10″, 10′″) using a data fusion algorithm, calculating adjusted global positioning data for the first road vehicle (10) and communicating (104) the adjusted global positioning data to a positioning system (6) of the first road vehicle (10).