wow,im getting approx 275-280 miles per 18 gl. tank,and my car is not running right,its got cold start issues,hesitations,popping in plenum when cold,i thought that 280 miles was pretty decent for a crappy running car,im only running it on 89 octane,not the suggested 91 like the book says,ive noticed it runs fine on 89 octane,no knocks,no pings,no preignision,i think these cars are supposed to average 24 miles per gallon on the highway,when running correctly.check you 02 sensor,it effects proper air fuel mixtures and can reduce fuel mileage.also .you may want to do an ohm or milliamp test on your E.H.A,this is used for accurate cold starts,but you will be surprised how it can effect the cars all around fuel issues.