A door drive device for adjusting and/or locking a vehicle door relative to a vehicle body, the door drive device comprising: - an adjustment member, - a drive element operatively coupled to the adjustment member such that the adjustment member is movable with respect to the drive element for moving the vehicle door relative to the vehicle body, - a sensor device for measuring a measuring quantity indicative of a movement of the vehicle door to provide a sensor signal, - a control device for controlling operation of the door drive device, wherein the control device is configured to detect, based on the sensor signal, an action onto the vehicle door indicative of a user command for moving the vehicle door, wherein the control device is configured to conclude for an action onto the vehicle door indicative of a user command for moving the vehicle door by evaluating a characteristic value derived from the sensor signal based on a decision parameter, wherein the decision parameter is variable depending on a movement direction of the vehicle door, wherein the control device is configured, for evaluating the characteristic value, to compare the characteristic value to the decision parameter, wherein the control device is configured to evaluate the characteristic value, by comparing the characteristic value to the decision parameter, to decide whether a user action is taking place for initiating a movement of the vehicle door from a currently assumed, opened or partially opened position, wherein the control device is configured to set the decision parameter to a first value for an opening movement of the vehicle door and to a second value different from the first value for a closing movement of the vehicle door, characterized in that the control device is configured to adjust the decision parameter based on at least one further sensor input from another sensor device formed by an inclination sensor. - an adjustment member, - a drive element operatively coupled to the adjustment member such that the adjustment member is movable with respect to the drive element for moving the vehicle door relative to the vehicle body, - a sensor device for measuring a measuring quantity indicative of a movement of the vehicle door to provide a sensor signal, - a control device for controlling operation of the door drive device, wherein the control device is configured to detect, based on the sensor signal, an action onto the vehicle door indicative of a user command for moving the vehicle door, wherein the control device is configured to conclude for an action onto the vehicle door indicative of a user command for moving the vehicle door by evaluating a characteristic value derived from the sensor signal based on a decision parameter, wherein the decision parameter is variable depending on a movement direction of the vehicle door, wherein the control device is configured, for evaluating the characteristic value, to compare the characteristic value to the decision parameter, wherein the control device is configured to evaluate the characteristic value, by comparing the characteristic value to the decision parameter, to decide whether a user action is taking place for initiating a movement of the vehicle door from a currently assumed, opened or partially opened position, wherein the control device is configured to set the decision parameter to a first value for an opening movement of the vehicle door and to a second value different from the first value for a closing movement of the vehicle door, characterized in that the control device is configured to adjust the decision parameter based on at least one further sensor input from another sensor device formed by an inclination sensor.