I'll post here because I'm too lazy to point you toward a number of threads that discuss this at length - and I mean no insinuation here.
But there is lots of info about SE gas mileage.
Riding conservatively in town I get 45 mpg
I regularly get 50 - 52 mpg at 60-65 mph
I have gotten over 60 mph on days when I kept it between 50 and 55 mph, burning more than a tankful.
As little as 40 mpg burning more than a tankful at 75 - 80 on the freeway.
The mileage on these bikes is very sensitive to road speed and agressive acceleration.
For my purposes I pay no attention to how much gas it consumes - I ride only for pleasure.