Method for operating a motor vehicle, having the steps of: - detecting a spatial position of at least a first body part of a vehicle occupant which is arranged in a detection range of a detection device of the motor vehicle with respect to the motor vehicle by means of the detection device; - providing an anthropometric data model which comprises data relating to the dimensions of predetermined body parts of a person and the positioning of the body parts with respect to each other; - establishing a spatial position of at least a second body part (26, 28) of the same vehicle occupant which is arranged outside the detection range of the detection device, taking into account the detected spatial position of the first body part and the anthropometric data model; - controlling at least one functional unit (32, 34, 36, 38) of the motor vehicle taking into account the established spatial position of the second body part (26, 28); characterised in that - a spatial position of a first shoulder of the vehicle occupant which is arranged in the detection range is detected and, taking into account the detected spatial position of the first shoulder and the anthropometric data model, • a spatial position of a second shoulder of the vehicle occupant is established and a height adjustment device of a seat belt of the motor vehicle is automatically controlled, taking into account the established spatial position of the second shoulder; • and/or a spatial position of a head of the vehicle occupant is established and taking into account the established spatial position of the head an air conditioning unit of the motor vehicle is automatically parameterised and/or a height adjustment device of a headrest of the motor vehicle is automatically controlled. - detecting a spatial position of at least a first body part of a vehicle occupant which is arranged in a detection range of a detection device of the motor vehicle with respect to the motor vehicle by means of the detection device; - providing an anthropometric data model which comprises data relating to the dimensions of predetermined body parts of a person and the positioning of the body parts with respect to each other; - establishing a spatial position of at least a second body part (26, 28) of the same vehicle occupant which is arranged outside the detection range of the detection device, taking into account the detected spatial position of the first body part and the anthropometric data model; - controlling at least one functional unit (32, 34, 36, 38) of the motor vehicle taking into account the established spatial position of the second body part (26, 28); - a spatial position of a first shoulder of the vehicle occupant which is arranged in the detection range is detected and, taking into account the detected spatial position of the first shoulder and the anthropometric data model, • a spatial position of a second shoulder of the vehicle occupant is established and a height adjustment device of a seat belt of the motor vehicle is automatically controlled, taking into account the established spatial position of the second shoulder; • and/or a spatial position of a head of the vehicle occupant is established and taking into account the established spatial position of the head an air conditioning unit of the motor vehicle is automatically parameterised and/or a height adjustment device of a headrest of the motor vehicle is automatically controlled. • a spatial position of a second shoulder of the vehicle occupant is established and a height adjustment device of a seat belt of the motor vehicle is automatically controlled, taking into account the established spatial position of the second shoulder; • and/or a spatial position of a head of the vehicle occupant is established and taking into account the established spatial position of the head an air conditioning unit of the motor vehicle is automatically parameterised and/or a height adjustment device of a headrest of the motor vehicle is automatically controlled.