I been having this problem when sometimes i pull someone over and backup arrives a few mins later patrol cars show up at that spot empty, and also i cant move them, i posted my log in another post but just today that post was removed and locked, so now i dont have the log anymore as i deleted it from my computer, as i start fresh evey time i load the game, this is the other post i responded to

so how do i fix this? as there is nothing telling me how to in that post and it was locked and my post removed

Can you clarify? Do you mean that when you pull someone over, you ask for backup and the officers leave the car or does the car have nobody in it? 

If it is the same problem I have seen, after a call out, especially one that requires a foot pursuit. The AI will just walk away, seemingly forgetting they drove to the scene. It clutters up the map and the AI civilians are left dumbfounded and have no clue how to get around a car in an intersection. 

I believe there is a command in the console to clean a plugins items up, since my V installation screwed up, you'll have to try to match up the command in the help command.