Fuel economy....

So, after living with the car for the last 5 months, when it is time to visit the pump after a normal week of driving, this is usually what kind of gas mileage I am getting:

Somewhere between 16.9 and 17.2 mpg, on average.  This is slightly disappointing, because while I might have a bit of a heavy foot, I typically cruise at no more than 5 mph over the limit - but worse, because my previous car, a BMW E60 M5, with its massive V-10 and 500 bhp, could do the same duty on about 12.7 to 13.4 mpg.  (Yes, I know that's abysmal, but I didn't expect big mileage from it.) 

I didn't buy this car for the gas mileage - but I guess I just thought that the difference going from a 5.0L V-10 to a 3.5L V6 (albeit a twin turbo) would be greater.

Also, I should clarify, this is on Premium fuel, 93 octane.  If I use regular, the numbers are slightly lower - not much, but the power loss is noticeable.