I have a 2021 GLS 580 with a trailer hitch. It seems to me that the sensor for the hands-free rear hatch is located to the left of the hitch as you are facing the rear of the car. Sometimes it works like a charm on the first kick, but on other occasions you can kick the air all around the area to the left of the hitch all day and it will not work. Of course, if you are trying to attach the trailer pigtail to the plug on the car, the rear hatch opens every time. So I guess I would say that it is reliably unreliable, kind of like many other features of the vehicle. For example, sometimes when I drop my iPhone on the charging pad with the ignition off, that act turns on the radio and sometimes, if the ignition is on and I move my iPhone in the charging pad, it changes the radio station.