Man maybe the brand of gas does make a difference! I'm only getting 13.8 city driving and taking it easy. Only tested it once or twice, just to see what she could do, and was very pleased. Guess I'll try a tank or two of Chevron or 76 and see what happens. Been using Wally world stuff half and half. From what I've seen though, the tankers all get their loads at the same refin/tank farm. See all the brands rolling out of there at one time or another.