I'm going to assume that you meant that you had the car running and power to the camera (so it was already recording), and you got out and pushed the car to simulate an impact?
What is your g-sensor level at? Low/Med/High.. Maybe you didn't push it hard enough
If you mean that the car was turned off and the camera wasn't running and you tried to simulate an impact, you won't get a recording unless it was hardwired for parking mode, and since the V1 3rd Gen doesn't have a parking mode function that means the camera would be recording 24/7..