Our mileage is terrible too. 1.6 AWD. 6700 miles. She drives it 20 minutes to work every day via the highway and we average around 21mpg every time we fill up. Even on long highway trips we are in the 23-24mpg range at normal (70-75) speeds.
We take my Corvette on long trips now, I can pull 28mpg@80mph easily.