How to keep old rare cars rare when adding them back into dealer

When adding rare cars back into the dealer I feel like the people that had it before it was re-released should get something to show that there car is a older one. this could make it so that those people that originally had the cars can make sure that their cars keep the rarity. This could be something like adding a livery/ sticker that could be applied to their car before you put the selected car out in the supporter dealer (maybe like a week in advance) and then email the people that have the car to tell them to add the sticker/ livery on. Then like a day before the cars do get added in the dealer remove the sticker/ livery from being able to be applied, this could make it easier to tell if people have a old or new car.