When the car is moving a bit faster the game limits the steering and full-lock is not possible.
When in drift, the limit applies only towards inside turn.
My suggestion: give controller players an option to remove this limit in simulation mode, so that the full steering range can be utilized with controller stick.
This has actually been a bit of an issue since FM4 in the Xbox 360 I believe that’s when they introduced speed sensitive steering in the game. Or maybe it was FM 3, not sure.
Many including myself have requested that they give the player control over this or the option to remove it altogether, but it seems they don’t want to make the game challenging and appeal more to casuals than actual motorheads.
In PCARS 2, Assetto Corsa or Dirt Rally 2 e.g. I can overdrive the car as much as I want or control her however I want around turns, it feels great. In Forza you can’t. Because of the on-rails assist around turns. I think they even removed torque steer when you take off from from the starting line.