@viofo is right that it works the same way as the A119, but since you are new here you may not know how the A119 works!
I have used parking mode on my A129 test sample by using a powerbank, which is like your constant 12v power as far as the camera is concerned.
After about three minutes without motion, the camera enters parking mode and waits in standby mode. It then uses motion detection (watching the scene) and starts a time lapse recording for a short duration if it sees any movement, then goes back into standby. When you start driving again, the camera stops parking mode and goes back to normal recording mode.
You can test this yourself by turning off the screen saver and sitting in the car when parked. Watch the screen after about 3 minutes and see what it does.