How you drive is more important than what you drive. And I don't mean how you keep it <4k rpm or whatever.
Put an 86 on a flat windless highway at 55mph for a day and it will get >35 mpg.
Downhill you might hit 40 mpg.
Put an 86 in stop and go traffic for a day and it will get 19 mpg.
Flog an 86 on the track and it will get 10 mpg.
Put a Prius on a highway at 75mph for a day and it will get <40 mpg and not the 50+ plastered all over the advertising.
Here's my fill up log, averaging ~24-25 mpg with a city driving bias. Highs of ~35, lows of ~10.
http://www.fuelly.com/car/scion/fr-s...7974/fuelchart
Here's EPA ratings for the car, you have reported absolutely nothing abnormal.
https://www.fueleconomy.gov/feg/bymo...ion_FR-S.shtml