The published EPA mileage is pretty much a pipe dream on this car. One needs perfect conditions to achieve those numbers. I’ve had 2 tankfuls in 4 years that met those numbers.
One thing I’ve noticed about the Outback is that one only needs to look at it cross-eyed for the gas mileage to nosedive. A cold engine, lots of stops, hills, head and crosswinds, and an individual’s driving style all affect results.
Given your initial description of things, my first question would be to ask about your driving habits. My wife has a lead foot compared to me, and she gets worse mileage in her 2016 Crosstrek than I do in my Outback. She should be beating me by 2 mpgs or so.
I’m comfortable with the gas mileage I get. While not to EPA figures, it is really quite reasonable for the size and type of car.