Custom Online Race Help

Hi can someone tell me if I can change the AI cars in a custom online race. In forza 4 when you setup an online race you can pick the specific car for each AI. is there a way to do that in Forza 5. Because I cant see where I can pick each specific car for each AI.

in fm5 you cannot change the ai cars . this is due to the drivitar system

but i think you can force the room to a certain car then ok it , after that change the room back to random it should keep them in the forced cars (this is an old fm4 trick might not work)