I never paid much attention to trip mpgs, especially short in-town trips versus long highway runs. There are just too many variables involved to get a good comparison.
To me a better judge is tank-by-tank, but even then there are a lot of variables which can affect a tank, even in my old Insights which could go 700 miles between fill-ups
You're probably doing nothing wrong, just keep at it and drive consistently and you'll see the numbers creeping up (weather permitting).
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