I only use A/C when itīs very hot (>30 °C) and I have a passenger or have to go somewhere dressed decent, too.
When itīs very hot I get up too 85 mpg with A/C off (2.7-2.8 l/100 km) on my commute, if I turn A/C on itīs really difficult to reach 60 mpg (< 4 l/100 km).
And if I really use the A/C, I use it mostly to decelerate the car downhill or if I have to brake anyway.