Pelked1,
AC?!? I've been using the heater!
Seriously, most of my driving has been done in the very early morning,4-5 am, and it has been a pretty cold summer. I'd say the avg. morning temp is in the mid to high 60's. (Between 42 and 74)

So, in the name of science, I made the great sacrifice of going on a long scenic "sunday drive" on a nice hot (for here) sunny day. No AC, but I did have the windows down. The temp was 82-83F.

Big change! I got 26.6 MPG! I was expecting a loss, not that much though! No flooring it or high speeds, just a leasurly drive.

I'm thinkin' if you want the best mileage you'll have to move to the frigid north, turn off the AC and not have any fun driving. And get a chip mod but don't use that gas pedal!
On the plus side, I do feel the car has more power on those chilly morning drives!

Matt
P.S. I never use less than 93 octane.