Can I suggest that the end of the long VIN number is the best one to use as the four digit number on the chassis will change if you change the chassis while the VIN stays the same.
I've just added mine to the list and used the serial number stamped under the driver's seat (948). Given this is an Oct 2013 car this is consistent with the 1,000th model.
It's also build number 83448 and the last 4 digits of the VIN are 2017.
Somewhat confusing
