Calculating Fuel Economy - Ford 2000 E-150 Owner's Manual

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.
For consistent results when filling the fuel 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.
Use a known quality gasoline, preferably a national brand.
Use the same side of the same pump and have the vehicle facing the
same direction each time you fill up.
Have the vehicle loading and distribution the same every time.
Your results will be most accurate if your filling method is consistent.

Calculating fuel economy

1. Fill the fuel tank completely and record the initial odometer reading
(in kilometers or miles).
2. Each time you fill the tank, record the amount of fuel added (in liters
or gallons).
3. After at least three to five tank fill-ups, fill the fuel tank and record
the current odometer reading.
4. Subtract your initial odometer reading from the current odometer
reading.
5. Follow one of the simple calculations in order to determine fuel
economy:
Multiply liters used by 100, then divide by total kilometers
traveled.
Divide total miles traveled by total gallons used.
Keep a record for at least one month and record the type of driving (city
or highway). This will provide an accurate estimate of the vehicle's fuel
economy under current driving conditions. Additionally, keeping records
during summer and winter will show how temperature impacts fuel
economy. In general, lower temperatures give lower fuel economy.
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