Well first of all Mr gti, calculated is only 1-3 less then displayed mpg. And calculated is somewhat erroneous as well considering the odometers are slightly off. So I would avg out the two for the best answer.
Second of all my numbers are so high because round trip I drive 3.5 hours a day through 50/55 mph roads with the last 20 mins on the interstate. So lots of highway miles with a hot engine. My short weekend drives are plagued with low mpg as well.
You can trade in your car for a nice price. These cars lose hardly any resale in first couple years esp to non-subaru dealerships.