I was up at 37 overall since June, but my last tank was calculated at just under 34 (display showed 36). My current tank is displaying 28.8, which could turn out to be 26!
I, too, have a short commute, 6 miles each way. Normally, though, I have one trip per tank of 50 miles each way and that tends to give me an MPG boost. This tank so far has been ONLY short trips--nothing over 10 miles. So, once I go on my "long" trip this weekend, I'm hoping to bring that number up some.
Clearly, short trips and cold weather really hurt. My previous car got 22-23 in the middle of winter on the same commute. So, it's still better.
The bad mileage also coincided with my first (and only so far) oil change. I sure hope the dealer didn't use 10w-30 dino oil! Of course, there's no easy way to know....