On three of the four trucks (the fourth truck may have the problem, too, I just can’t recall) we’ve conducted mileage testing on, the odometer’s are off by 1 to 4.9 percent. The odometer’s read low, and the discrepancy between actual miles traveled and the odometers widens as speed increases. We’re told that many of the Ford’s odometer’s may have been calibrated wrong from the factory. If you own an ’11 you owe it to yourself to validate your odometer’s accuracy. You may find that your truck gets up to 5% better mileage than it’s leading you to believe.
Example 1:
Trip: Cross country road trip (Michigan - Colorado)
Model: ’11 Ford F-350, four-wheel drive, XLT, crew cab, 3:73 gears, DRW
Tires/Wheels: 245/75R17
Speed: 65-66 mph
Error Test: From mile-marker 167 to 67 (100 miles traveled), odometer read 96.4 miles traveled
Error: 3.6% (chart above, courtesy of Harry Rawlins)
Error’s Effect on Mileage: 16.3 mpg (truck) Vs. 16.9 mpg (actual)
Example 2:
Trip: Cross country road trip (Michigan - Colorado)
Model: ’11 Ford F-350, four-wheel drive, XLT, crew cab, 3:73 gears, DRW
Tires/Wheels: 245/75R17
Speed: 75-76 mph
Error Test: From mile-marker 132 to 32 (100 miles traveled), odometer read 95.1 miles traveled
Error: 4.9%
Error’s Effect on Mileage: 15.0 mpg (truck) Vs. 15.8 mpg (actual)
Example 3 (Project 6.7L Power Stroke):
Trip: Two, 10-mile runs up Interstate
Model: ’11 Ford F-350, four-wheel drive, XLT, crew cab, 3:55 gears, SRW
Tires/Wheels: 245/75R17
Speed: 60-65 mph
Error Test 1: 10 miles traveled, odometer read 9.8 miles traveled
Error Test 2: 10 miles traveled, odometer read 9.7 miles traveled
Error: 2-3%
Error’s Effect on Mileage: 16.9 mpg Vs. 17.3 mpg
Plan: Mileage and Odometer error will be thoroughly determined on next trip to dyno (200-mile round trip).