Yeah, everything off. I never even pushed the rl car to the limit, yet it drove a million times better than the one in the game. It really feels like the one in the game has no sway bars and its not just that car in particular, its all of them.
In the game, you are pushing it hard. If you push the M5 hard in real life it will be slide happy.
At the track I always push cars to the max or atleast close to it, just make sure the track has lots of run off areas
Then again its a game and Forza cars does feel like they slide around, but when looking at the speedo in game, its at 40mph or higher when they slide around everywhere.
I slide around a lot in autox and thats avg 20mph though turns.