Anyone who has played ACC on a gamepad will immediately notice that the most common form of steering on that game (which is to push the steering stick up to 0 degrees to drive straight, and then roll it left or right along the sticks circumference to steer) is not possible on FM.
I am not a student of video game design, nor do I fully understand what causes this steering method to not be possible in FM, but the way it calculates steering inputs and deadzones seems to be the cause.
In ACC (and many other games) when setting a deadzone of 2% and using this method of steering, it seems that inputs from 358 to 2 degrees are ignored, allowing easy dead straight driving with corrective inputs that are further modified by the large list of settings available to customize. Forza seems to take a wildly different approach. This, coupled with the lack of input modifiers causes this radial steering method to be virtually impossible.
I suggest that more modifiers be added to the Advanced Controller settings menu, with options to change the way deadzones are implemented as well as more sensitivity adjustments. Current steering inputs with controller are very twitchy and binary. Watching the field of drivers take a slight bend in a Multiplayer race is somewhat comical, and cornering in general is a very on/off affair with even smooth linear stick inputs being suddenly interrupted by non adjustable factors like speed sensitive steering.