okidoki, so the recommended fuel is 91 right? Well, I usually put in 89 or 91 depending on where I can get it, and the occasionally wallet lightening 93. But I've also read here that fuel technology is more advanced now, and that todays 91 is the equivalent to the 80's 91 octane. But anyway, why is it that even if I drive my car harder, I get better fuel mileage with 87 octane over any other. I usually put in Exxon, but notice a slight difference in power between other brands. I've kept this experiment's independent variable as Exxon gas. So all I've been using lately is Exxon. I've gotten about 5 more mpg with 87, than 93. And almost nothing more with 89. When I noticed that I was getting better mileage with the 87, I started to drive it harder, and thats when I came up with the average of about 5 more mpg. Am I imagining this, or is there a logical explaination??