My husband swears that he gets better gas mileage using premium...

If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in switching to higher octane gasoline.

Octane Myths

• High octane gasoline improves mileage.
In general, if your car is designed to run on 87 octane gasoline, high octane gasoline will not improve mileage. If switching to high octane gasoline does improve mileage, you might find that your engine, or its control systems, need repair.

• High octane gasoline gives quicker starting.
No, it doesn’t.

• High octane gasoline increases power.
If your car is designed to run on 87 octane gasoline, you shouldn’t notice any more power on high octane gasoline. Again, if it does make a noticeable difference, your engine, or the engine’s electronic control systems, may need repair.

• High octane gasoline has been refined more – it is just a better product.
Additional refining steps are used to increase the octane; however, these additional steps do not necessarily make the gasoline a “better” product for all engines. They just yield a different blend of hydrocarbons that burn more slowly. The additional steps also increase the price.