Accuracy of Truck Fuel Usage Data Called Into Question

October 12, 2015

By Today's Trucking

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Relying on the electronic data from a truck’s engine computer may not be the most accurate gauge of fuel economy, according to a not-for profit engineering and research group for the North America trucking industry.

The report from Performance Innovation Transport Group details electronic control module data precision and accuracy between engine manufacturers and among engine models from a single manufacturer.

The study compares engine ECM data with actual test track fuel consumption and was conducted in the fall of 2014 on 14 different vehicles with engines from four manufacturers. The test track evaluations, which followed the Joint TMC/SAE Fuel Consumption Test Procedure Type II, compared fuel consumption data provided by the engine ECMs, a procedure that is generally regarded as an industry standard for testing.

“The ability to measure fuel consumption accurately and precisely and defend the results is critical for writing vehicle specifications, for establishing effective maintenance practices, and for training drivers to operate vehicles as fuel efficiently as possible,” said Yves Provencher, director of PIT Group. “Our tests show that engine ECMs present different levels of precision and accuracy, and that ECM data should be used with caution for evaluating the impact of a fuel saving technology or operational practice.”

A copy of the full PIT Group technical report is on its website.

PIT Group is a subsidiary of FPInnovations, formed in 2008, to provide what it says is an unbiased, neutral testing organization to help manufacturers evaluate and refine prototypes and fleet managers select the best technologies to reduce costs and environmental impact.


  1. 1. João Reis Simões [ October 13, 2015 @ 03:34AM ]

    All methods for measuring fuel consumption have produce an error. The importance of the error depends on the purpose of the comparisons of the figures, for instance when two makers are involved or the comparison is with real life figures. Whenever those figures are used in different situations of service for one vehicle the conclusions are valid.
    At an operator, the values of fuel consumption (gallon) derive from the purchase, and here errors are also present. The same can be said for miles, tons and ton-miles. Albeit, correlation between those value can contribute to significant understanding of fuel efficiency.

  2. 2. Cliff Downing [ October 13, 2015 @ 04:49AM ]

    There is only one fool proof method, break out a calculator and take miles from last fill and divide by gallons put in the tank over several fill ups and you have your true fuel economy. I realize that it seems quaint to do it this way, but if you want accurate data, you sometimes have to revert to solid ways of getting it. I have yet to see an ECM readout that gives accurate fuel economy to even within 1 tenth mpg.

  3. 3. Paul Darwin [ October 13, 2015 @ 05:41AM ]

    Cliff is absolutely right on this. Call it old fashioned if you will, but it is accurate.

  4. 4. Hanne Hansen [ October 15, 2015 @ 08:38AM ]

    João is absolutely right. All measures are a 'best method' calculation based on assumptions. Even distance, which is part of the fuel consumption calculation, is a 'best method' calculation. Based on our experience with GPS vs. odometer, even a vehicle's odometer is only accurate to a point; it can easily be + / - 2-5% of actual distance travelled. So knowing what the assumptions are behind a calculation is important. Cliff & Paul are also correct that keeping track of fill ups will at least tell you the fuel consumed.


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