I have been playing around with settings a lot tonight. All I can say is yes it is notchy around center in Gran Turismo. I will continue to mess with game and wheel settings to see what there is. Tonight I only ran high downforce cars in the drc 24. That is part of it, I also think tires play a part in gt6. Too much tire on a car can feel like a high downforce car.
I think your wheel is fine and it is just the firmware and and game we are playing. If you are still concerned though, I would highly recommend contacting Fanatec. (They will want a simple short video to accompany your concern. Just a heads up) If it is defective, the normal turnaround is very fast I'm sure. Today though we have some dock problems with their US landing point. Very sad and whole nother discussion. Part of me says we all need better pay, but I have not seen a raise in years and these dock workers earn 140,000k a year US. So I am on the fence.
So sorry to go tangent. Let's share some GT6 settings that we like. Personally I play on long stretches and need a lower beating, otherwise my wrists become damaged and painful, to the point they wake me up.
Right now at DRC 24 min.
Sen 900, ff 90, sho 40, abs off, Lin off, dea 20 (messing with 10 to 30), drl off, for 60, spr off, dpr off. In gt6 settings max torq 3, force feedback sensitivity 10.