1. Fill the Tank: Completely fill your fuel tank to the top. Record the odometer reading at this point. This is your starting odometer reading.
2. Drive: Drive the truck normally under typical conditions for a significant distance (at least 100 miles, preferably more for better accuracy, especially if your truck has a large fuel tank).
3. Refuel: Again, completely fill the tank to the top. Record the amount of fuel added (in gallons). Also, record the new odometer reading.
4. Calculate: Here's the calculation:
* Miles Driven: Subtract the starting odometer reading from the ending odometer reading.
* Gallons Used: This is the amount of fuel you added in step 3.
* Miles Per Gallon (MPG): Divide the miles driven by the gallons used.
Example:
* Starting odometer: 10,000 miles
* Ending odometer: 10,500 miles
* Gallons added: 25 gallons
Miles driven: 10,500 - 10,000 = 500 miles
MPG: 500 miles / 25 gallons = 20 MPG
Important Considerations for Diesel Trucks:
* Consistent Conditions: Try to maintain similar driving conditions (speed, terrain, load) throughout the test period for more reliable results. Varying conditions significantly impact fuel economy.
* Multiple Fill-Ups: For even better accuracy, repeat this process over several fill-ups and average the results. This helps smooth out variations from one tank to the next.
* Regenerations: Diesel Particulate Filter (DPF) regeneration can temporarily lower fuel economy. If a regeneration occurs during your test, it might skew your results. Try to avoid this if possible.
* Fuel Quality: Using higher-quality diesel fuel can slightly improve MPG.
* Truck specifics: Your truck's weight, tire pressure, and aerodynamic modifications (or lack thereof) will impact fuel economy. Don't compare your results directly to someone else's without considering these factors.
By following these steps and taking into account these considerations, you'll get a reasonably accurate calculation of your diesel truck's fuel mileage.
