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I’ve tried this exercise many times. It just doesn’t work. If you sit in the car it detects you and stays on. If you try to get out of your car you wake it up by opening the door.
So maybe if you have long enough arms to hit the power off button while standing outside the car with the window down and then very quietly walk away you might be able to get the car to shut down. My arms weren’t long enough to test this out so I gave up.