With exhaust i added a few tenths and the cover raised it to 15.5 mpg. I added the 1714 with premium fuel and im getting 14.3 mpg . Man the tuner is fun LOL.

 

You'll never jack up your MPG's enough to make any kind of impact on your pocket book.

All the suggestions here are going to cost you hundred's of dollars and take years to recoup your costs.

Go buy a Prius if you want milage, or that new Escape Hybrid.