An operating device for a vehicle comprises an outer unit that can be rotated manually, a detection device configured to detect the movement of the outer unit and generate a control signal using a value that characterizes the movement to control a vehicle function, and an actuator unit that contains a magnetorheological medium, which can be or is coupled to the outer unit and is configured to exert a retaining force on the outer unit based on the viscosity of the magnetorheological medium. The operating device also comprises a sensor unit located in the outer unit and configured to generate a hand signal indicating the absence of a user's hand on the outer unit, and a manipulating device for manipulating the control signal on the basis of the hand signal.