* Regular unleaded gasoline: This was the most common fuel type for the various engines offered that year.
* Premium unleaded gasoline: Some higher-performance engines may have *recommended* premium gas for optimal performance, though they might not be *required* to run on it.
To know for certain what fuel *your specific* 2009 Ford Fusion uses, check the fuel cap or your owner's manual. The fuel cap will usually have a sticker indicating the recommended octane rating.