Dear blazerdriver-  The government (www.fueleconomy.gov) says you should be happy if you are getting 14-22 mpg. I haven't heard proof of a chip that would help you.  You will find ads for chips that will improve your mileage, just as I find ads for golf clubs that will give me an extra 50 yards off the tee.  I have a closetful of them, but still can't reach Tiger.  Really, the factory installed chip generally aims at the best economy your engine can provide with acceptable performance.   Good luck from Bovan.