I’ve been thinking about vehicle speed lately as the Federal Motor Carrier Safety Administration has once again delayed its truck speed limiter rule until May of 2025, and diesel prices have been trending downward.
When diesel prices are high, more fleets look at ways to reduce fuel consumption, and slowing down is a good way to get more miles from a gallon of fuel. The axiom is that for every 1 mph over 65 mph, there is a corresponding 0.10 mpg decrease in fuel economy. When fuel prices are low, that can seem less important, but the reality is that fuel economy should always be a top priority.
Many people cite the fact that drivers are against having speed limited, and while I think driver input should be given serious consideration, there are other factors to include in the decision of whether to limit the speed of your vehicles.
See also: FMCSA’s plans for AEB systems, speed limiters
Safety is another argument for limiting speed, even if it is not mandated. According to the Federal Motor Carrier Safety Administration, speeding is a major contributor to crashes, injuries, and fatalities. For example, the agency found that speed-related crashes claimed 11,258 lives on U.S. roadways in 2020. And in that same year, speeding was the most frequent driver-related factor in fatal crashes for commercial vehicle drivers.
American Truck Business Services reminds us that a truck’s “sweet spot” is the rpm that is most efficient for the engine. ATBS says that running an engine in the sweet spot requires that the truck be driven at a constant speed that is usually lower. Running in the sweet spot can lead to less wear and tear on the vehicle, which could reduce maintenance and repair costs.
Driver acceptance of limiting speed is one concern, but other concerns are that if trucks go slower, fleets will fail to meet delivery windows or may even have to add more trucks or drivers to make the same number of deliveries.
A good way to address this concern is to look at your vehicle routing. Optimizing routing should allow you to make the same number of deliveries with the same number of trucks and drivers, even if those trucks are going slower. Consider doing some route modeling to see if it is possible to make minor adjustments to existing schedules so that you can slow your trucks down. Even if you choose not to limit speed either at the pedal or on cruise control, a route optimization exercise can improve your fleet’s overall efficiency.
When evaluating whether to limit the speed of your vehicles, make sure to consider the potential safety benefits as well as the impact on durability and longevity.
