Wow something doesn't seem right. I keep hearing of people with TSXs getting bad gas mileage while others are getting good. I have about a 60mile commute daily and its a 50/50 of highway and stop and go traffic on the way home. I'm averaging 30mpg on my fill ups and it isn't like I'm hypermiling in neutral, which in fact I am always in gear unless I'm at a stop.
Besides maintenance things like oil changes, filters, and checking your tire pressure, your driving habits are your best bet for improving mileage. Since you work so close I'm guessing you are mainly doing city driving. Accelerate slowly and be in the tallest gear (if you have a manual transmission) to keep your revs down with out lugging the engine. This is a hardest concept for people to understand that drive manual. If you don't need to accelerate quickly, then there is no need to be in the higher rpms that have more power. This is what I love most about our close ratio manual transmissions. There is always a proper gear for city putting without being in excessive rpms. I'm usually shifting between 2500-3000rpms depending on the situation.
Also try to catch the greenlights. If I see a traffic ahead of me waiting for a greenlight, I usually slow down early in hopes of the light turning green and traffic starting to flow by the time I get there. Sometimes I get lucky, sometimes I don't. Hope these tips help. Also use premium. The end.