Originally Posted by Hommersimpson

its been proven 55mph will get you the most MPG

Originally Posted by sheepdog

but anyway i have just been down shifting anytime i feel it get to full throttle, and been surprised with my mileage. i have been comparing octane, and at least in my jeep, it makes a big difference. my driving is pretty consistant, one trip to work at 60 miles round trip, one trip highway to school, 120 miles, one trip to work, then fill up, if i havent already, drive to school, drive to work, fill up, then its the weekend, hang out. i have found with 85 octane from maverick (pretty much only option around here) i average 16.8-17.6, average 17.1, and its been very consistant, and that is calculating in the extra miles gained from the 31 inch tires over the stock tires. but moving up to 91 octane, i average 18.6-19.7, average 19.15, and have gotten over 20 a couple times, thats with a 4" lift and 31x10.50 tires, so from what im seeing thats only an average of 2 mpg drop over the stock set up. and, when its $0.20 more a gallon for premium, if im totally empty, it would take right at 20 gallons to fill it up. so, 0.20 times 20 is 4, so im paying a maximum of $4 more for a fill up to run premium over 85, and im getting an average of 2.05 mpg increase, so for 4 dollars more if i run all 20 gallons out, im getting 41 miles farther, and its probably better for my engine anyways.........so i have pretty much decided that it saves money to run premium, just for the gas mileage, if not for the life of the engine