I dont know how slrr is inferior in controller support as I dont have a controller and I dont generally play racing games so I wouldn't know when the control feels right. I heard there is someone who added xinput for win10 maybe you are looking for that (LINK) but as I said never tested this.
Also there are numerous settings in the advanced control settings with those you ought to be able to customize your experience to your liking.
But if there is something specific that is not already in the game like a factor to modify how fast the given pedals are pressed I can look into it (though I think these particular factors are already in)
