Gas mileage?

I just got my bike earlier this week and went through the first full tank in a single day. I calculated my mileage and it was 38mph. Keep in my mind this was my first real day with the bike so I wasnt even abusing it or riding it really hard. I read some reviews on the bike and the writers claimed to get 38mpg out of theirs on a track.

So i'm just curious, what kind of mileage do you guys get when you just kind of take it easy, and what are some things I can do to improve my mileage?