I made it out to Charleston, WV from Detroit on one tank, thats right, one tank (434 miles). I have always belived it was the result of using Amoco Ultra Gasoline with 1 bottle of Gas Saver (like, $0.99). Have not had anything major changed on my car yet (like O2's, ect.), so, maybe try switching up your gas. Have you thrown a bottle of GOOD fuel system treatment in your tank yet? I'm talking 10-12 dollarstuff, like moble 1 synthetic fuel treatment ($10.99), I used that about 4 months ago, and have noticed a huge diffrence in mileage. And don't use that "dollar store alcohol" stuff they call "fuel system treatment"

. Give that a try.