IIRC, the better MPG for the A/T version is basically due to the assumptions of the manufacturers that M/T drivers will drive the car more aggressively.
I mean, I've got the M/T and am averaging 31-33 MPG when I'm driving normally and shifting sub 4kRPM.
On a side note, I love all the hassle of the M/T. Even in traffic. It's fun rev matching, heel-toeing, and using all 4 limbs to drive. It's a game. I have a Infiniti G37S now and had an IS350 in A/T and even though they have paddles, it's not the same. My mind drifts and I end up just driving it like a non-paddled A/T. Gas/Brake...
Plus, the M/T keeps my wife from ever driving the car
