I'm curious how you managed to get 57.8 mpg (displayed) over 700 miles. I'm perfectly happy with my FFH's mpg but it's always about 47+ mpg (displayed) in my suburban driving.
It's how, where, and when I drive. First, I drive gently - no excessive speed, or sudden starts and stops.
Second, my commute is in central MD. If I drive toward the mountains to the west, my economy drops. More surprisingly, when I drive east of the Chesapeake Bay, where it's almost completely flat, my economy also decreases. So, gentle hills seem to optimize economy for me.
Third, my rush hour commutes are usually in some traffic, which lowers my average speed to about 40 or so, which seems to also be optimal. In short, I think I drive in some very favorable conditions to get the most out of my car.
Conversely, my wife gets about the same as you with her 2014. Her driving and commute are very different from mine.