I have only about half the cars in the game, so this must be a bug.
If I auction a car, it will be offered back to me as a reward almost straight away. Since the last update it’s got so bad that I’m exploiting it by selling certain cars at auction that always sell for a good price, knowing that they will come straight back… and they do: yesterday I sold the exact same car at auction 4 times over. There is no way that is happening by random chance, given there are so many cars I dont own and have never owned.
Now, I can go on doing same thing and make a pile of credits every day doing it, but I really would prefer to get some different cars offered as rewards, ones I don’t own and have never owned. So if Turn 10 decides to look at this, please consider removing from the pool of cars offered as rewards all those the player has previously auctioned or sold - because if you sell them you probably don’t want them back!!