Have you done the little tricks mentioned here on the board?
53 is still great mileage but I bet you can get a little better. You don't mention speeds, traffic situations (freeway, hills, city w/ constant stopping etc.). 53 "might be" stellar for your particular situation.
You're right though, most people can acheive better mileage with a stick.
I have faith you can squeeze just a few more MPG's out of that Insight.
