At 44 mpg you're already at 137.5% EPA rating for the car. Thats really pretty good. If you want to hit the really high numbers, you have to either look at going slower, serious aeromods, or pulse and glide. Sounds like you weren't a bad driver to begin with.
You can also try accelerating a bit harder. I use the "LOD" function on the scangauge and keep it around 80 while accelerating. Do that, and keep your rpm under 2000.
It also just takes time too. Look at
my fuel log in the Paseo for instance. Its just a gradual incline as I learn how to better use all the techniques available.