How do you really know that you’ve improved your fleet’s efficiency? On practically every page of any given issue of Fleet Equipment, we detail all the latest equipment options that aim to boost fleet efficiency—from engine and aerodynamic improvements to telematics and service solutions. As a fleet manager, you’re looking for any and every edge over your competition. Yet, when it comes down to it, how do you know that new truck order or aerodynamic investment is going to pay off for your fleet? The only way to know for sure is to test.
The North American Council for Freight Efficiency (NACFE) partnered with Carbon War Room (CWR) to form Trucking Efficiency, a group that issues a series of Confidence Reports that focus on the integrity of test data to prove fuel efficiency improvements. The latest report boils down efficiency testing details to provide fleets a snapshot of available testing methodologies. The five methods investigated included:
1. Computer model-based testing—specifically, computational fluid dynamics analysis;
2. Wind tunnel testing;
3. Track testing, including coast down testing;
4. On-road testing; and
5. Fleet composite evaluation testing.
The report also stated that within those methods, real-world factors can impact individual fleet efficiency findings, and so Trucking Efficiency also investigated potential impact from the 14 most common such factors:
1. Ambient temperature;
3. Rain and snow;
4. Road surfaces;
5. Road grade;
6. Tractor configuration;
7. Vehicle maintenance level;
8. Manufacturing assembly and reassembly tolerances;
9. Ice, snow, mud and dirt;
10. Driving profile (duty-cycle);
11. Traffic aerodynamics;
12. Vehicle and component age;
13. Driver behavior; and
14. Measurement system precision.
Let’s cut to the chase—what’s the best test to run for measuring efficiency? Unfortunately, there’s no simple answer. In a conference call explaining the report’s findings, Mike Roeth, NACFE’s executive director, explained that you have to know what your testing objective is and consider how your fleet operates on real-world roads.
“For example, fleets are interested in determining the improvement in fuel efficiency of a component relative to its own specific specs, trucks and trailers,” he said. “On the other hand, a manufacturer is testing based on how its product may perform across hundreds of different specs: How will it work on day cabs vs. sleepers? How will it work on double trailers compared to single? Different wheelbase or powertrain combinations?”
Method matters. Your fleet is in constant motion and so is your efficiency target. In terms of efficiency claims from manufacturers, Roeth explained that it’s important to adjust claims to your real world operations and be comfortable with a “fuel efficiency range.”
“You might hear someone say that a component will get 2.8% fuel economy when it was run on a track test at a fixed mile per hour,” Roeth said. “When the fleet looks at its operation, they don’t operate trucks at that speed all the time, so it’s important to be comfortable with the range.”
The big takeaway from the report is to seek multiple methods and look for trends in the data.
“Don’t fall in love with a single test—that holds true for fleets and manufacturers. One test is just that: one test,” Roeth related. “Multiple tests allow you to look for trends in test data. That’s where we think the most confidence in a [efficiency] number can be found, and then take that number and adjust it to each fleet’s real-world operation.”