Horizon stabilization in rF2, even when set to high, is not even as effective as world movement set to 0 in AMS2. The horizon still moves a bit. If you want the same amount of horizon movement as rF2's horizon stabilization set to high, set world movement to around 30.
And yes, the car moves around a bit more in AMS2 with low world movement, compared to rF2, because...the car moves around a bit more in AMS2 compared to rF2...
And you can't have a static cockpit and a static horizon. The car is moving. Either you stabilize the camera to the horizon, in which case the car appears to move a lot, or you "bolt" the camera to the car, in which case obviously the horizon will be bouncing around, because the camera will be fixed to the car. You can adjust the ratio between the two options by adjusting the world movement higher or lower, but you can't make the movement disappear.