I am a sporadic user of the AC, so that certainly must help my figures. The fact I don't need to use my car in rush hour or have any time schedule to keep, means I can conentrate on eco driving.
I know once we have cooler weather, and if my car does more town work, I would expect to be getting late 40's, like the Honest John figures. Mind, I don't think I've ever recorded less that 46mpg in my Jazz.