Hello and welcome to the site bkrell. The first area to focus on is driving technique. You'll see your best and cheapest gains here. Check out our list of driving tips here:
http://ecomodder.com/forum/EM-hyperm...ecodriving.php
Pick out a few and watch them increase your FE, then try a few more.
Other than the driving tips I'd look into aero mods as your traveling at high speeds. Check out the aerodynamics forum and its sticky.