How does a car sitting there idling drop into reverse?
Well, let me tell you. It happened to me with my 78 Dodge Diplomat. I almost won the Darwin Award that year.
I drove around the corner on my way to work. I live on a corner and my garage is on the side street. The wife was flying some windsocks from the plant holders on the posts in front of our house. One was on the ground. Who would think that that could have killed me.
I was late, but I thought I would put it up so I pulled to the curb and "threw" it into Park. PRNDL There is a tab between Park and Reverse. If you don't get it firmly seated in the Park position, the cam or whatever the proper term is, can rest on the tab. The idling of the car can work the shifter down the tab and eventually it will "fall" into Reverse.
By then I was out of the car on my front porch. I heard a clunk and turned around only to see my car backing around in circles in front of my house. Every time it came to my curb, the front wheel would catch and turn the steering wheel causing it to complete another circle. I wondered what to do, call the police? What would they do, watch it? I looked down the block and saw a car at the corner a couple of houses down. He did the same thing that the police would do, watch in awe until it crashed into a house.
When I saw the pattern repeating itself, I thought of the circus horses and ran out in the middle of the street and sidestepped with the car. My only problem was my car idled at 25 MPH (was going to take it in) and it was going around at a pretty good clip - not normal by all means. Pulling the handle of the door was not opening it as the centrifugal force kept it shut. My last effort was to put my right hand on the body and open it with my left. Since the door was going to sweep me under the vehicle, I had to make my move fast and dive into the car. Amazing how fast the brain works as I planned my strategy in one or two revolutions.
I pulled and the door opened. I dove. The backward force threw me to the floor of the car. I felt the car bounce as I was thrown around. My only thing to do was to apply pressure to the brake pedal with my left hand. The car stopped. While pressing on the brake, I reached up and turned off the key. When I knew I was safe, I slowly sat up and found my car sitting in my neighbor's front lawn, ten feet from his gas meter. He since has had it moved to the side of his house.
Started the car and drove to work like nothing happened. Went past the guy still sitting at the corner, his jaw still dropped to his chest. Okay, the last 7 words were fabricated. The rest is true.