Have you changed your driving habbits at all? See this for some tips ->
100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com
Also welcome to ecomodder
.
What I did for my corolla was find what MPH gave me the best MPG, and targeted to keep as close to that speed as I can (45mph). Some areo mods would throw you over 45mpg I bet.