Because fuel typically represents one of a fleet’s highest operating expenses, it is good practice to periodically review driving practices and behaviors with truck drivers that can reduce wasteful driving habits and lower emissions.
Drivers have a significant impact on fuel consumption—both good and bad. Studies have shown that in fleets with identically spec’d trucks, a driver can have as much as a 35 percent impact on the fuel economy, which is based solely on driving techniques.
Even highly experienced drivers can boost their fuel-savings, skills and driving performance through continual training.
Vehicle speed has the largest single impact on fuel mileage. The faster a truck runs, the more fuel it consumes. Advise drivers to reduce speed to a reasonable level. A general rule of thumb is that every mile per hour (mph) over 50 mph reduces fuel mileage by 0.1 mile per gallon. Besides being dangerous, speeding also can put extra stress on the entire vehicle, as well as the driver.
Remind drivers that constant changes in speed reduce fuel mileage. Extra fuel is burned every time a driver needs to regain speed. Drivers are better off a few miles an hour slower than surrounding traffic to avoid constantly speeding up and slowing down.
Moreover, emphasize to drivers to operate their vehicles at lower revolutions per minute (rpm) in the appropriate range and cruise in the engine’s “sweet spot”the point where power and economy are highest. In many of today’s heavy diesel engines that is around 1,300 to 1,450 rpm. For engines produced in the late 1990s and early 2000s, the sweet spot is about 1,600 rpm.
Rather than accelerating downhill, drivers should let gravity do the work and leave the accelerator alone. Gravity will increase the vehicles’ speed.
If vehicles are equipped with cruise control, drivers also should be prompted to use it where appropriate and coast whenever possible. Cruise control optimizes the engine’s electronic control system’s ability to deliver the appropriate amount of fuel for any given situation and this helps improve fuel efficiency.
Another common driver habit that reduces fuel economy is poor anticipation of upcoming traffic conditions. Failing to anticipate traffic tends to result in too-frequent stops and starts, plus unnecessary idling.
Also remind drivers to develop a smoother driving technique to avoiding sharp acceleration, which is often called “jack-rabbit” starts, and rapid or hard braking as these increase fuel consumption.
So, too, does taking circuitous routes. Out-of-route miles result in burning more fuel, as well as lost time. Estimates are that out-of-route miles may account for up to 10 percent of a driver’s total mileage each year.
Routes should be checked periodically to assure they are optimized for fuel mileage. GPS tracking and intelligent route planning systems can help reduce wasteful driving habits as well as improve workforce productivity and customer service.
Frequent and improper shifting also negatively impacts fuel economy. Every time a driver drops down a gear fuel consumption increases.
Techniques such as block-shifting (going from, for example, second gear to fifth gear); progressive shifting (upshifting at the lowest rpm possible); and starting out in a gear that doesn’t require using the throttle when releasing the clutch will help reduce fuel consumption.
In addition, teach drivers to eliminate unnecessary idling as it wastes fuel and increases emissions. Drivers should be encouraged to shut off the engine whenever possible, for example, if they anticipate a lengthy delivery or pick up, or are stuck in a traffic jam.
Depending on the size of the engine and accessory loads, an engine can consume from 0.5 to 1.5 gallons per hour while idling with the air conditioning running. For every 10 percent of total running time an engine is allowed to idle, fuel economy is reduced 0.1 miles per gallon.
Instruct personnel not to overfill vehicle fuel tanks, especially during hot weather. Fuel expands when it is hot and can be heated by both the sun and by fuel returned from the engine or fuel system. If the fuel tank is filled to the brim when the fuel expands, its only way of escape is via the breather vent.
Be certain drivers are diligent in doing their pre- and post-trip vehicle inspections and are reporting any deficiencies or problems. Also be sure service personnel are correcting all reported issues and paying particular attention to any noted performance problems that may be decreasing fuel mileage.
Vehicle maintenance
Ongoing, proper vehicle maintenance is a critical element in the fuel economy equation. Vehicles that are well maintained operate much more efficiently and squeeze more miles per gallon out of every tank of fuel.
Here are some key points to keep in mind:
  • Because clean fuel is critical to engine life and performance, monitor the fuel quality at the pump and replace vehicle air and fuel filters at the proper intervals.
  • Keep all wheels and axles properly aligned to minimize rolling resistance, which reduces tire wear and fuel consumption.
  • Repair body damage and cracked, bent or broken aerodynamic devices as these may create additional drag.
  • Properly maintain tires. Poor tire condition and improper inflation are major contributors to reduced fuel economy and also adversely affect vehicle handling, traction and braking. Tire rolling resistance accounts for about one-third of a truck’s fuel consumption.
Tread depth over the life of a tire has a significant effect on tire fuel economy as well. As a tread wears, the fuel efficiency of the tire usually increases. The increase is fairly rapid at first, and then slows as the tire wears out.
This change in tire wear affects the rolling resistance in different ways between brands and compounds, thus changing the fuel economy over time.
Keep in mind that a tire designed for high mileage life will not yield the best fuel economy because of its deep tread. However, a tire that is classified as a fuel efficient tire likely will experience reduced tread life because of its shallow tread.
Incentive programs
Consider a driver incentive program to reward drivers for enhanced performance and fuel economy based on factors within their control. For example, the program could be based on idle time, vehicle speed, and maintaining or exceeding a target mpg.
Incentive programs are effective because they focus attention on specific areas and, at same time, reinforce desired behavior by rewarding and recognizing a job well done.
Successful incentive programs set attractive and attainable goals and are simple to administer. They must also be perceived as fair to drivers. The criteria for any incentive needs to be well-defined and well-communicated with built-in controls to ensure that rewards are awarded appropriately.
What’s more, to be successful, incentive programs need to provide rewards regularly and frequently. Unless drivers continuously see the rewards for their efforts, momentum drops along with the added motivation. Successful programs provide timely and consistent rewards in a way that meets expectations and brings satisfaction.
Fleets that have developed successful driver incentive programs typically ask drivers or special driver committees for input regarding goals, reward criteria and the rewards and acknowledgements. They also make other employees aware of the driver incentive programs, particularly those whose job affects the driver’s ability to perform as expected. BI