I know this is obvious but folks often forget: MPG is directly related to the amount of work you're asking your car to do. As such, it's usually not helpful comparing MPG numbers with each other because we're all asking for different things from our cars. I've had tanks ranging from 35.9 MPG (all-highway road trip) to 22.8 mpg (a week when I drove to work and averaged 6 miles per hour).
As they say, YMMV. There are so many variables to consider, so the best you can do is to drive another car through the same environment and see how your Focus does relative to that.
2014 Ingot Silver - Electric (current)
2012 Oxford White SE 5-door 5M 203A + Sport Package (sold)