Fleets wrestle with choosing the right metrics when it comes to making decisions on which technologies to invest in to improve the efficiency of their vehicles. In his 2015 Society of Automotive Engineers Buckendale report, Fuel and Freight Efficiency — Past, Present and Future Perspectives, Rick Mihelic, NACFE’s director of emerging technologies, summarized the complexity of commercial vehicle fuel and freight efficiency.

For all types of vehicles, including trucks, we typically look at gallons of fuel paid for at the pump and the miles driven on those gallons. From that fleets estimate average miles per gallon (or kilometers per liter) of a truck and then use that same information on all its trucks to determine the fleet-wide fuel economy.

But averages might not be a good way to compare one technology to another when trying to make a purchase decision. And the decision is complicated by the fact that precise controlled tests rarely reflect real-world conditions. For test results to be useful for fleets they need to be both precision (aka repeatable) and accurate (reflecting the real world).

MPG numbers stated by vehicle and device makers as a measure of a technology’s performance in a fleet are not necessarily precise or accurate.

There are other measures fleets can use to determine efficiency such as freight ton efficiency, which adds freight weight to the MPG value and results in the measurement of freight on miles per gallon. Fleets might combine the freight ton efficiency from all its trucks by using net freight weight carried, net fuel used, and net miles driven. As the payload gets heavier the freight miles per gallon goes up, but ironically the MPG goes down. So, how one defines efficiency is critically important.

Neither of these measurements takes into consideration the physical volume of freight carried — cube. This basically is the density of each shipment.

Adding cube data with freight weight, fuel efficiency, location, traffic density, etc. would give fleets one single metric they could reliably use to evaluate technology.

That may be beyond the scope of what many fleets want to do. The bottom line is that if you want to improve something, you need to measure it. Whether you use MPG, freight ton efficiency or some other metric, you can see how one technology might be an improvement over another in your particular fleet and you see how your fleet is performing overall.

The good news is that advancements are being made in measuring the real-world factors that fleets are subjected to and that should help fleet managers to be able to better evaluate new technologies based on how they will perform on the road not in a wind tunnel or on a test track.

My advice is to pick a measurement and track it regularly for each truck in your fleet. Note any deviations on either side of your average to determine what is working for your fleet and what isn’t. Then make decisions based on what you learned so you more of your trucks will start being above average and then you can establish a new, better average.

After all, it is about continually making steps to go from good to better to best.

Michael Roeth has worked in the commercial vehicle industry for nearly 30 years, most recently as executive director of the North American Council for Freight Efficiency. He currently serves on the second National Academy of Sciences Committee on Technologies and Approaches for Reducing the Fuel Consumption of Medium and Heavy-Duty Vehicles and has held various positions in engineering, quality, sales and plant management with Navistar and Behr/Cummins.