Don't know about the 550, but on the 380, the motion sensor for the parking capture is really sensitive.Got everything squared away with hard wiring and its fully working! Wasn't too difficult to install and run wires through the car. This thing records front and back, so I feel somewhat better when I park the car or if sh*t* happens. Here are some pics.
Also I find that the videos captured while driving are mostly "Event" videos, not "Normal" ones. I have a feeling that the software doesn't compensate for normal gravity in the up/down plane, and so exceeds 1G at the slightest bump.