How to Improve Fleet Fuel Efficiency by Making the Right Spec Choices

Diesel fuel prices may be down today, they may tick up tomorrow, but no matter the cost historically, fuel costs still represent a significant portion of a fleet’s cost of operation. So any improvement in miles per gallon is a welcome cost-saver. While trucks coming off the production line today are more aerodynamic than ever, dealers can still make choices to help their fleet customers squeeze every tenth of a mile from a gallon of diesel.

Start by Adding Aerodynamic Devices

Aerodynamic drag plays a large role in the fuel efficiency of a truck compared to passenger vehicles. Overcoming both wind and aerodynamic resistance requires more horsepower and fuel than it would if this drag were reduced. According to Cummins, for every 2% reduction in aerodynamic drag, fuel economy is improved by approximately 1%.

According to the North American Council for Freight Efficiency’s (NACFE) Tractor Aerodynamics Confidence Report, improving the fuel economy of one diesel truck from six to 10 mpg means 6,667 fewer gallons of fuel burned over a 100,000-mile year. This reduces costs and emissions by over 40%.

Fortunately, there are a number of devices that can be added to a tractor or trailer to reduce aerodynamic drag. These include cab extenders, roof extenders, tractor-trailer gap reducers, chassis fairings, drive wheel fairings, wheel covers, trailer rear devices, and more. According to the NACFE report, on 53-foot van trailers, fleets can see a 2% to 4% improvement in fuel economy with chassis fairings, often called chassis skirts. Other devices result in smaller fuel economy gains but still provide savings.

There’s also an opportunity for aerodynamic improvement on trailers, especially van trailers. Aerodynamic drag can be addressed in three main areas: gap, underbody and rear. Devices on the rear of trailers modify the airflow as it leaves the trailing edge of the side and top surfaces of the trailer.

Choose the Right Tires

A tire’s rolling resistance refers to the force needed to keep the tire rolling at a constant speed on a level surface. Rolling resistance accounts for 30% to 33% of the total fuel cost of a modern Class 8 truck. Some tires are specifically designed to have lower rolling resistance.

The U.S. EPA SmartWay has a list of low rolling resistance tires that can serve as a guide when helping fleets choose the right tire for their application. These tires have demonstrated measurable fuel savings.

Tire pressure monitoring systems can also ensure better fuel economy. An oft-quoted trucking industry statistic is that 10% underinflation will cause a 1% loss of fuel economy. Tire pressure monitoring and tire inflation systems monitor both tire pressure and temperature and alert the fleet when tire pressure falls below the recommended level. This allows the fleet driver to take steps to bring tires back to proper pressure or, in the case of inflation systems, to reinflate tires to their proper pressure level automatically.

Manage Engine Parameters

Electronic engine parameters are software settings for diesel engines that can be adjusted or customized to improve fuel economy. Parameters can be created to set vehicle speed both at the pedal and in cruise control. Cummins says that at speeds higher than 55 mph, each 1-mph increase in vehicle speed decreased fuel economy by 0.1 mpg.

There also are parameters for idle reduction that govern how long an engine can idle before a shutdown timer turns off the engine. Idling can be costly to a fleet. Industry estimates are that for every hour of idling, fuel efficiency decreases by 1%. In addition, many state and local regulations set fines for idling over a specific amount of time.

Other Considerations

Once you’ve worked with a fleet to spec a vehicle that’s as fuel-efficient as possible, there are additional ways to help them. Remind them about the need for proper maintenance. Manufacturers set preventive maintenance recommendations for a reason: to ensure that trucks operate as designed and spec’d to. Encourage fleets to follow manufacturer-recommended preventive maintenance inspection and service schedules.

Also, work with your fleets on their driver training programs so that drivers understand their impact on fuel economy. American Truck Business Services has developed a list of 25 ways drivers can improve fuel efficiency, including using momentum and cruise control, which drivers can easily implement into their daily routines.

Addressing aerodynamic drag and tire rolling resistance are good starting places for improving a vehicle’s fuel economy. Coupling that with setting engine parameters focusing on fuel efficiency can lead to significant fuel economy gains for fleets. Strong maintenance practices and proper driver training will also allow fleets to get more miles from a gallon of diesel, leading to big savings.