Been running the AC consistently in the afternoons on my way home, and still broke 70 mpg on the last few tanks, although this last tank I just barely made it
Mornings I really don't need the AC, I just keep the windows cracked, and I don't take that much of an aero hit since I have the rain guards on the windows. Afternoons it's just too hot to keep it off, even though it's losing me between 3-7 mpg to run it, so I crank it.
I'm finding out that breaking 70 mpg while running your AC is not an easy thing to do. I refuse to hold up traffic on my commute trying to hypermile, so I'm also doing it while hanging with all those folks on I-4 at 65-70 mph! Well, the ones in the slow lane anyway . . . since the ones in the fast lane are doing 85-90