I did something pretty dumb yesterday. Left home yesterday and left my cell phone on the roof of the car when exiting the garage. Drove slowly and when accelerating from a stop sign heard a bump along the side of the car and then remembered what caused noise as it fell. I made a u-turn and hurriedly parked at the side of the intersection. I pushed the park button on the drive selector stalk, opened the driver door and jumped out of the car to fetch the remnants of my phone before it was run over by another car. Much to my surprise, the Model S continued to drive forward at about 4 mph as I stood along side. Fortunately I was able to hang on to the door and swing back into the drivers seat. I pushed the park button again, got out and the same thing happened and this time I jumped back in and hit the brake pedal and then pushed the park button which stopped the car. Fortunately this happened on a quiet neighborhood intersection and there were no causalities. I discovered that the brake pedal needs to be applied before the park button engages. On level ground the "creep" setting generates about 3-4 mph which is helpful on hills in San Francisco but something to be aware of if the car is still in drive mode. BTW, I found phone case, back plate, battery and phone in pieces. Put it back together and it still works!