I looked on Fuelly after getting the GTS 250ie to get an idea of what to expect for mpg. Until my last two fill-ups, I've been seeing around 74mpg pretty consistently. That seems to be a bit better than the average on Fuelly, so I'm good with that.
We have been in the Black Hills the past week - here to enjoy some cooler weather and great roads. We lived here 12 years ago, and are very familiar with the outstanding riding in this area. We have been riding pretty aggressively on fun, twisty back roads; avoiding highway riding as much as possible. I figured on/off throttle through the curves and changing elevation would have driven the mpg down. (That has been my experience with previous motorcycles.)
One fuel up ago, I got 84 miles per gallon. Yes, the tank was full. I thought that was a fluke. Fueling up today... 87 miles per gallon! A new world record (for me)!
The elevation has been between 3,500 and 5,500' for most of the riding; rarely above 50mph, but running into the corner, picking a line, and accelerating out... it has been a blast! I thought the mileage would suffer. Nope.
On that same tank, my wife got her best ever on her Honda PCX: 118 mpg (her average is around 106 mpg).
This was a low mileage bike (around 1,400 miles on it when I bought it two months ago)... maybe it is opening up? Maybe the elevation? Maybe it likes these twisties as much as I do?
Whatever the reason, I like it!