Being new, the car won't get the best mileage right out of the box. . . it takes a while to settle in the new engine, transmission, driver, etc.
My first tank full was appallingly low, too. Maybe not 22mpg but around 26. But then I considered that most of the driving I was doing was all town - mostly 35 - 45 mph. It has gotten better over the months.
Relax, don't drive it like a dragster, and it will improve for you.