Roeth: Day cabs can benefit from aero devices

Jan. 24, 2024

Fleets would benefit from aerodynamic devices more than they think, especially when it comes to day cabs.

Much of the attention on trucking focuses on the long-haul segment dominated by sleeper tractors. But a great deal of trucking is shorter hauls, much of which is covered by day cabs. In fact, according to our friends at ACT Research, over 40% of all Class 8 tractors sold are day cabs.

I believe operators of both sleeper tractors and day cabs want to operate as efficiently as possible and get the most miles out of a gallon of fuel. I also suspect far too many people in the trucking industry think that aerodynamic devices are only for sleeper tractors. They believe investing in aero devices on day cabs makes no sense.

They are mistaken.

In the first place, many erroneously believe there is no aerodynamic benefit at speeds under 50 mph. That simply is not true. There are still efficiency gains to be had, though payback could take longer. It is important to remember that for every 2% reduction in aerodynamic drag, there is approximately a 1% improvement in fuel economy. Even if a truck does not get a full 2% reduction in drag, it still can see some improvement.

I would also guess that many fleets—especially regional ones—spend more time at highway speeds than they think. I challenge fleets to spend some time analyzing their data, looking at miles traveled at various speeds. Of course, there will be slower miles as they get closer to their delivery points, but unless they are in a 100% city delivery application, I bet they will find that their trucks are traveling at more than 50 MPH for long periods.

Additionally, when looking at the tractor-trailer as a complete unit, there are plenty of opportunities for aerodynamic improvement. The tractor-trailer combination can be optimized for aerodynamic efficiency even if the tractor is a day cab. For instance, gap closure devices between the tractor and the trailer are particularly beneficial as they tend to have higher gaps, creating more drag as the air hits the front of the trailer.

If you are operating day cabs, I encourage you to consider adding aerodynamic devices. I bet they will save you money.

About the Author

Michael Roeth | Executive Director

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 (NACFE). He 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.