Car Moved On Its Own. Any Ideas?

User error. No mystery here.

It certainly isn't a broken parking pawl -- this would have happened without any sort of intervention in that case.

Finally -- OP never actually mentioned what transmission mode was selected when she got back into the car. I have little reason to believe it wasn't N or D.

 

8 days later? embarrassment

 

The OP use's the phrase:

So "moving into drive" makes me think when she entered and pushed on the brakes...the car was in D.
The OP's contention is that it moved into D on it's own.

To be honest reading the OP's post I'm just glad it wasn't a bigger tragedy. 21 weeks pregnant, moving around the vehicle on ice, and a vehicle that for whatever reason, does start moving is a very dangerous situation. Thank God, it was just a matter of being able to get in the vehicle and hit the brakes.

I can't diagnose "why" or "how" the vehicle started moving by itself. If the OP is 99% sure it wasn't user error? Then I'm not going to try to convince her it was user error....because I can't be 100% it was.

Therefore my only advice is BE CAREFUL. In that situation, even a low speed collision with your neighbors car, is better than slipping and falling around a moving vehicle.

I'm the type of person that IF I believed I didn't make a mistake? I probably would want the vehicle checked out.
Even though the scenario that it was simple user error is the Occams Razor, simplest most direct answer. In this case? I'm OKAY with investigating against the odds here. Better safe than sorry.

Glad the story ends ONLY with a trip to the dealership.

 

Certainly when the car it’s in D and resting on flat pavement you can get out the car and car will not move until the engine kit in again that will be when the car will roll start moving by it self giving the wrong impression that it drove away by itself but not it just was let on D, yes it happened to me.

 

This is not my experience with the Prius. Unless there is some initial resistance to hold the car still, the car will roll on the flat, whether the ICE is running or not. Certainly, the ICE kicking in may just be enough to overcome any initial resistance, if that was stopping the car from rolling initially.

 

Sure that’s exactly what I mean I may not have my self explained correctly, when the ICE kick in whatever resistance holding the car will be overcome, thank you.

 

While your foot was on the brake you swung your purse or jacket sleeve and pushed the shift lever into neutral. Then you failed to recognize the warning beep that sounds when you open the door and the car is not in park.