This is not really a relevant metric with the rental fleets. As cars move around and get re-plated, oftentimes they change plates multiple times, even during the year or two they're in the fleet. I once rented a Fiat 500X that was on a Kansas plate, but in the glovebox were prior registrations from Utah and Florida. It seems as though as cars come off fleet and head to auction/sale, the station will remove the plates, and then recycle them to vehicles with expiring plates or new vehicles. For instance, I know the DTW station has a rotation of plates that all date back to the middle of the decade (2012/2013) but they just affixed those plates to brand new 2018 vehicles.