Been reading a lot of how the Forza physics engine and it's gamepad buffers work. It seems like the engine, even with simulation steering enabled has the ability to modify the steering lock and possibly even grip multipliers for the front axle to smooth out corner entry. This is obviously necessary because you have about 1/2" of thumstick travel to correspond with a center-lock range (which is like 450 degrees of rotation!) of the actual steering wheel. So here's what I think is happening.
-At high speed turn-in with a 911, the front tires are going to be extremely sensitive to losing grip because they have such little weight over them
-The game provides a 'buff' to the amount of lock requested by the player, slowing down the input
-At the same time, I THINK the game gives a proportional, momentary amount of extra grip to the front axle, effectively pinning it to the ground
-The rear axle receives no such parameter adjustment and is left twisting in the wind, literally
-If the game is not modifying grip values, I think it is adding yaw to compensate for the understeer.
Basically, I think the game is trying to compensate for what would be a huge amount of initial turn-in understeer by dramatically increasing front tire grip momentarily. This would explain why the car actually handles reasonably well once it's taken a set in a corner and why it behaves largely as expected on my roundabout test. It's the control buffers screwing with things. All of this I think explains why cars start to feel more unrealistic the fast you go in Forza games, and why I'm typically down in the B, C, and D classes. The control buffers just distort things more and more the fast you are going. I'm gonna do a test later with the telemetry on to see if my theory has any merit.
During testing, Greenawalt noticed people liked to tap the analogue stick of the controller in the opposite direction of the turn to incrementally adjust their angle. “If you go full opposite lock with the steering wheel every half second like this, the car is gonna be out of control,” he says. “So we put a buffer between the controller and the physics layer.” This buffer compensates for the player tapping the stick, ensuring the car doesn’t spin out when they do.
“The other strategy is having clamps and scales on how much yaw, which is the torque of the car, can be applied to the spinning skater. Using these clamps, we can slow a car down without changing the moment of inertia. When you play with simulation steering you turn this feature off, as well as a lot of the buffers, but even I have trouble playing Forza like this with a [gamepad’s] thumbstick.”
I realize that simulation steering is meant to deactivate all these buffers, but if you look at your telemetry while driving, it is clearly still running in some capacity.
edit: For 225mph challenge, I was able to beat it with a Ford GT. However, the stock engine could not give enough power (which is insane, because those engines have made more than 2000hp IRL) so I swapped in the V10 and gave it twin turbos.