My 1st "new" vehicle so not 100% certain BUT from what I was told (by several dealers) that at some point Ma Mopar gives them a time limit (on "older" models) to either sell them or buy them. So the dealership registers them in their name. They are now a "used" vehicle.
I checked another 2017 demo out at a different dealer and it had 10 kms (again no zeros). Didn't buy it due to color.
IMO I saved 15k or more off purchase price.