You have a much better average than me. I'm somewhere between 17.x and 18mpg at best. Full tank of premium (or whatever that gas station's highest octane is) is 350 miles or so.
Dealer has inspected car and fuel system more than once and has found zero issues with it. Apparently it's the terrible stop and go traffic here in South Florida.
2014 Infiniti QX60 AWD (every available feature except tow package)
2017 Ford Mustang GT Convertible
2014 Ford Escape Titanium
2014 Toyota Camry SE