The G8 GXP will have a manual though. It's got the LS engine as well. I'd rather have that anyways.
Some people don't want the highest package though. Me, personally, I'd rather pocket the $7k USD difference in price and have a 6spd GXP.
The bottom line to the effect on CAFE is nearly pointless. The G8 will most likely be Pontiac's lowest selling model. Even at 50K per year, how many would actually opt for the V8 6spd GT? or the GXP? Of the 20k that buy the GT, maybe 5K will buy the 6spd manual. 5k sales, in the grand scheme of things, will not bring down GM's or Pontiac's CAFE score. AFM only works if you baby it, and let the car drive your habits, which 95% of buyers of ANY vehicle won't do.
The idea behind bringing the Commodore over here as the G8 was the fact that little had to be changed to do so. From what I remember, the Commodore doesn't have AFM at all, on either transmission. They also offer a manual on both engines. Regardless, neither does the manual version of the Charger, 300, 3 or 5 series, Maxima, Avalon, Genesis, Impala... Oh wait, only the BMW's have manuals... never mind then! They already make LHD manual V8 and V6 cars for other markets, so there's no plausible reason other than pure laziness.
Silly old GM, they get the vehicle right, and they STILL find ways to push away conquests.