I know absolutely nothing about this genre (except minor details about Project CARS), so I'm just gonna take a guess.
Forza Horizon 2: 81
Driveclub: 85
Project CARS: 83
*What are those guesses based on? Well, it's very hard to please critics these days so I don't expect any of these titles to hit 90. Driveclub seems to have quite some hype going for it, so it's ranked the highest, whereas Forza 5 'only' got a Meta of 80, so I predict Horizon 2 to get 81. As for Project CARS, I can only guess, but I've seen some footage which looked pretty good and the game is also a popular topic of discussion.
Lyrics: He He He He Ha Ha Ha!