I think manual is better in many ways. I've noticed while racing in GT3 and GT4 that when in automatic, the car will shift to a gear during a corner, that you dont want it to be at. Such as the 1st corner at Deep Forest Raceway. Normally the car in Auto, will go to 1st gear and then move up to 3rd by the time you exit the corner. When I use Manual, I downshift to 2nd...and stay in 2nd gear until I reach the middle of the apex and then upshift to 3rd. This may not be accurate, but this is what I've seen in the past, or atleast I remember seeing. Anywho, I think manual offers greater freedome in choosing the speed through a corner, if you want to fly in with a slower exit speed...then manual works fine. If you want to enter a corner slow to have a greater exit speed, then manual works fine also. Well those were my 2 cents.