A computer is programmed to divide respective data of a first high-resolution map of a first geographic area and a second high-resolution map of a second geographic area into a plurality of respective subsets, assign one of the subsets of each of the first high-resolution map and the second high-resolution map to a first vehicle and a second vehicle, identify respective locations of the first vehicle and the second vehicle and the one of the first high-resolution map or the second high-resolution map that includes the locations of the first and second vehicles, and send, to the first and second vehicles, a map dataset that is a result of applying an XOR function to (1) the subset of the identified high-resolution map including the location of the first vehicle and (2) the subset of the identified high-resolution map including the location of the second vehicle.