Nope no calculations involved really, what it does is lerp the current steer towards the goal steel.
local function lerp(start, goal, alpha)
return start + (goal - start) * alpha
--Notice the similarities with the below steer equation?
--local steer = steer + (steergoal-steer) * math.min(deltatime*seat.TurnSpeed,1)
--alpha is equal to
@ThanksRoBama explains the equations behavior and hence it’s purpose in another similar post:
Provide responsive fast controls but doesn’t directly go towards the goal so you can do stuff like tapping input in order to control the car better at small turn speeds.