: You know it happens all the time ! She is doing something you never do in a car ! Maybe lifting her feet from the accelerator right before the shift or right after , or puts the lever between D - N or ... I watch my wife to drive sometimes and she is all different ! Womans have a different opinion about driving. I drive because I enjoy it she drives because she wants go from point A to B. Also she said to me one day when I told her not lift the gas of right before shift - how do you know it'll shift ? She won;t hear an engine noise or at least not recognize the different. So My suggestion is get in a car with her you as a passenger and ask her to drive like she'd normally do. Ask her to make stops, turn-off the ignition, turn-on, etc. everything, including hard acceleration! You'll see when it happens ! That should give you and a mechanic a good clue to search for trouble. Maybe the oil level is too low ! PS. Don't tell her that she is doing something because then she'll watch what she is doing ! Usually they think everything they do is oke, but better not to tell them first ! You might be suprised what'll happen and promise me you'll not be mad at her ! Good luck !