You don't use automatic transmissions for track cars. It's embarrassing and there's no way you can beat a manual stick, both in acceleration and control.
It's been a long time since I last drove at the Nurburgring. One needs to know one's car well, and memorize the track's every turn and road gradient in order to do well.
I think I should fire up my GT4 on my PS2 again. Hopefully my PS2 still works.