I have an iPhone 6s and I used to think I needed to simply wake the phone. That worked in those rare scenarios where the unlock did not happen properly when I pulled on the door handle. Then I discovered something else. I keep my iPhone in my back pocket. Simply the act of bringing the phone out in front of me closed the distance to the door as I was standing there. And that did the trick. I think the sensors for unlocking work within a few inches all around the car. Maybe someone can do a proper experiment.