Does Higher Octane Fuel Increase MPG?

More money equals better quality; Right? And better quality gas will make my car run more efficiently and therefore my gas mileage will be positively affected! Big Wrong! For the most part; cars run practically the same whether you have 87 or 91 octane in the tank. The vast majority of cars and trucks can run on the cheapest gas with no problems. It is only those cars with high performance engines, turbos, or superchargers that NEED to run the highest octane fuel sold. “Many high-performance engines are designed to operate with a high maximum compression and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. This is not true. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.” (http://en.wikipedia.org/wiki/Octane_rating)

Consult the owner’s manual of course. Most of the gas we get comes from the same source. Octane does not refer to the energy level of a fuel but to its resistance to auto-ignition or detonation. Detonation is a leading cause of engine failure. But if your auto can run on 87 octane; then go for it. The only thing that will happen is you will save 20 cents per gallon.

http://www.consumertipsreports.org/the_truth_about_highoctane_gas.html
http://www.wanderings.net/notebook/Main/IsHighOctaneGasWorthTheMoney