2000 Ford Focus Owner's Manual - Page 224

Maintenance and care The amount of Empty Reserve varies and should not be relied upon to increase driving range. When refueling your vehicle after the fuel gauge indicates empty, you might not be able to refuel the full amount of the advertised capacity of the fuel tank due to the empty reserve still present in the tank. Filling the tank Use the same filling rate setting (low - medium - high) each time the tank is filled. Allow three automatic click offs when filling. Always use fuel with the recommended octane rating of a known quality gasoline, preferably a national brand. It may seem insignificant, but you should use the same side of the same pump and have the vehicle facing the same direction each time you fill up. The driver should also have the vehicle loading and distribution the same every time. Your results will be most accurate if your filling method is consistent. This is also true when calculating fuel economy. 224