I have a '97, 2.5L, ATX with over 147K miles now. From day one, I only used Sunoco and Mobil. I would drive miles out of my way, or on fumes to get these brands of gas. I usually buy 92 octane. I tried 87 octand when I first got the car (new) and it pinged most of the time. 89 would also do it sometimes, but 92 would never.
As for getting 22 MPG, or even worse 17 MPG, I don't have the foggiest how that person could get mileage that crappy. Worse mileage that I ever got was 24.5 with just about all city driving. Best highway mileage has been just over 30, with an average of about 26.5 most of the time.
