The disclosure relates to a method to operate a portable input device 4 to control a motor vehicle 2. The input device 4 has a pressure-sensitive touchscreen 6. The input device 4 generates control signals S to control the motor vehicle 2, and transmit said signals to the motor vehicle 2. The control signal S has at least one determinable parameter P. The input device 4 is designed to capture a pressure value D of an actuating force of the touchscreen 6, and determine the parameter P according to the captured pressure value D.