For better gas millage, try using the lowest recommended octane for your car. The lower octane gas is also cheaper. Most modern cars are engineered to run most efficiently on lower octane fuel, and often recommend not using higher-octane fuel. Check your owner's manual to be sure, as not all car engines should use lowest octane gas. And speaking of octanes, did you know that you can mix octanes? In some areas, the lower octane may be too low for your car and the mid-grade or higher octane may be more than what you need. To avoid overpaying and still get the correct octane for your car you can mix the gas. For example, if your car takes 87 octane and the pumps have 85 octane and 89 octane, then when filling your car, fill half the tank with 85 octane and the other half with 89 octane and this will give you an equivalent of 87 octane plus it will save you money because the lower octane gas costs less. Thoughts?