[Gealii]

Hello. If i was in your position i would do 3 things first

1. Driving habits, hypermiling will do wonders for your mileage for me it was about 6 mpg change in my grand am

2. Buy a gauge, I would recommend either a scangauge or an ultragauge to help out with monitoring your fuel economy. Using a gauge allows you to play a game with fuel economy by getting a better high score where the score is your mpgs

3. oxygen sensors, not so much the post cat sensor, but pre-cat changes your fuel ratio causing you to burn more fuel then necessary. On MOST cars the post cat sensor doesn't change anything

Doing all this you should be able to pull mid 20s