Herein is disclosed a vehicle sensor-data sharing device, comprising one or more processors configured to receive sensor information representing sensor data output from the one or more sensors of a first vehicle; determine a reliability indicator indicating the reliability of the received sensor information; determine from the received sensor information a criticality indicator indicating the criticality of the received sensor information for the first vehicle; select a data sharing level based on the criticality indicator and the reliability indicator; and generate a message comprising observation information or a request for observation information, wherein the observation information corresponds to sensor information according to the data sharing level.