In order to impart a pleasant brake pedal feeling to the operator in the transition from a ‘conventional mode’ to a ‘brake-by-wire’ mode, it is disclosed that the travel (s) covered upon application of the brake pedal is determined and subsequently reduced by the operator, and in that upon reduction of the actuating travel (s) by a predetermined value (Δs) or in the event of a detected vehicle movement or a positive result of a monitoring function of the connecting and disconnecting device running in the background, the connecting and disconnecting device is activated and the brake booster is actuated by the electronic control unit.