The North American Council for Freight Efficiency (NACFE) has issued a new report to help fleets determine which fuel-saving devices and practices work as advertised.
The organization looked at five basic test methods widely used today, including: computer modeling; wind tunnel testing; track testing; on-road testing; and fleet composite testing, in which a segment of the fleet will be equipped with the device and compared to the portion of the fleet that is not.
NACFE’s Mike Roeth urged fleets to consider data from all the available testing methods before deciding to invest in a technology.
“Seek multiple methods and look for trends,” he said. “Don’t fall in love with a single test; one test is one test. Where we can have multiple tests and look for trends with different test data that’s out there is where I think the most confidence in a number can be found.”
The NACFE report indicated “there is no single correct method for fuel economy evaluation and each test has costs and complexities that need to be considered.” NACFE also pointed out the industry will benefit greatly from the more widespread sharing of test information.
“Having realistic expectations around payback of technologies is vitally important so fleets make the right decisions about which technologies make sense for them,” said Rick Mihelic, NACFE program manager.
The study revealed six insights that should serve as best practices for fleets, truck and trailer OEMs, manufacturers and others looking to validate the savings offered by technologies.
Understand Accuracy vs. Precision: The terms accurate and precise are not interchangeable. Precise is how closely a test result will be repeated by additional tests. Accurate is how well the test compares to a known reference value. Claims that a device is precise does not mean it is accurate. These two terms are often misused or incorrectly conflated.
Recognize that Data Exists and Sharing is Needed: A large amount of testing data for various technologies from various individual manufacturers exists already. It is mainly kept private, even when no competitive advantage is gained. All stakeholders should work to uncover and share the best available data for decision making. This will also reduce the resources being spent on redundant testing.
Clarify Objectives: All stakeholders should be clear in advance on what their review of testing data seeks to confirm or discover. For instance, manufacturers may want to learn how a device performs in many configurations and duty cycles, or may want to determine a metric such as drag coefficient, while fleets may want to confirm how a device performs in their very specific configuration and duty cycle, or seek a metric such as fuel burn. Different testing methods would be most appropriate for each.
Adjust to Real-World Operations: The results from various tests must always be adjusted to the particular duty cycle under consideration before paybacks can be calculated. For example, track testing may have been performed at a consistent speed of 65 mph, but trucks in a fleet may spend the majority of their time at 58 mph – such deviations must be overlaid onto the test results.
Be Comfortable with a Range: Adopting many proven fuel-efficiency technologies can reasonably be expected to improve performance, but the exact degree of improvement will depend on a fleet’s specific operations, and will likely vary over time in response to many other real-world factors. The metric of “degree of improvement” is likewise key; efforts to determine efficiency should be conducted relative to a baseline of current performance, and not an absolute.
Seek Multiple Methods and Look for Trends: In determining efficiency, multiple sets of test results likely cannot be compared or averaged in order to determine the exact performance of a technology. Rather, data from a variety of test methods should be considered side by side, keeping the particulars of each method in mind, in order to look for trends and gain confidence on results such as the minimum efficiency gain a technology will offer.
NACFE has been busy of late, publishing a new study every month. It has also created a Resources page at TruckingEfficiency.org, where fleets can find more tools to determine a payback on the various technologies in the marketplace.
The full Confidence Report on evaluating efficiency can also be downloaded free of charge at TruckingEfficiency.org.
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