The cars that i've seen with that are DLC cars that are on your save data but not on the ps3 that you're playing on. If it is DLC cars you are talking about, just redownload them from the PSN store. If you are talking about cars you've won, just try restarting your game. Im not sure what else to do if that doesnt work besides deleting your update data (DONT DO THAT UNLESS YOU HAVE ABOUT 5 FREE HOURS)
When does it put up the exclamation marks(maybe the signal like "!" though) next to some of your cars? When you open the list of your owned cars or the window?
