with the windows down, 80-85 mph, mostly highway (>80%) I got 32 mpg with my last tank.
the '11 has a slightly taller 5th gear, so you should be able to do better.
ac does take up to 15-20 hp.. on a bigger engines its less of a drain.. keep in mind there are a lot of factor to fuel economy than just engine size, epa estimates, etc.