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Getting the right specs for fuel efficiency

Image: Jim Allen/FreightWaves

With the rise and fall of fuel costs over time, managing fuel consumption is becoming more important to anyone involved in the trucking industry. The North American Council for Freight Efficiency (NAFCE) reported that the national average truck fuel economy is 5.83 miles per gallon (mpg). Therefore, there is certainly room for improvement. 

The average mpg of a truck is dependent on the truck’s overall typical operating weight. According to the  American Transportation Research Institute (ATRI), “fleets that reported loaded operating weights between 40,001 and 60,000 pounds had the highest fuel economy (7.2 mpg), followed by fleets operating between 20,001 and 40,000 pounds (6.8 mpg).  Unsurprisingly, LCV fleets typically operating at weights in excess of 80,000 pounds reported the worst fuel economy, with an average of 4.9 mpg.”

Further, ATRI reported that the average marginal fuel cost for motor carriers is $14.50 per hour on the road and is 22% of the total cost of ownership of a Class 8 vehicle.

Fuel efficiency is a major focus area in the design of recent Class 8 models and each year, buyers are given more options when it comes to spec’ing their truck with fuel economy in mind. According to, aerodynamically spec’d trucks improve fuel economy by a 2 to 1 ratio and for every 2% increase in aerodynamics, truck owners can expect a 1% increase in fuel economy. 

It is incredibly important that buyers consider all of the options they have when it comes to designing a truck around their own needs, including fuel efficiency. Navistar, Volvo, Freighliner, and Mack are just a few of the many manufacturers that offer a diverse range of features that maximize fuel economy. 

“Spec’ing a vehicle for the perfect combination of fuel economy and performance can be daunting,” stated Jim Natchman, marketing director of Navistar. “That’s why International offers PMG Aerodynamic packages that bundle all of the right aerodynamic options for your application.” 

These packages include all of the engine components, transmission, and axle, as well as shift parameters, rear axle lubricant, near axle ratio and more, all of which are proven to help manage fuel consumption and improve fuel efficiency. 

When it comes to selecting specifications individually, rather than in a bundle offer, it is important to select the right engine. Allison Athey, product marketing manager for Volvo, stated that the most efficient engine it offers in the VNL is the D13 Turbo Compound (TC) engine. Further, to maximize fuel efficiency, Athey recommends pairing the D13TC engine with the right aerodynamic features. 

One of the most commonly used words when discussing fuel efficiency is aerodynamics. Typical aerodynamic specifications include a sloped hood and grille, bumper with integrated air deflector, aerodynamic mirrors, etc.

Kelly Gedbert, director of product marketing at Freightliner, recommends additional features such as longer side extenders, rear wheel covers, and enhanced chassis fairing skirts. She also adds Detroit rear axle features such as lower sump volume, friction reducing gear cutting and optional axle lubrication to reduce parasitic loss as well as improve fuel economy. 

Aerodynamics is key to maximizing fuel economy, according to Roy Horton, director of product strategies at Mack. He stated that the three most important things to consider when spec’ing your truck for fuel efficiency are engine size and rating, transmission, and aerodynamics. 

The Run-on-Less Report by NAFCE lists the following recommendations for actions the industry should take in consideration of fuel economy:

  1. Use downsped powertrains and AMTs
  2. Educate and incent conscientous drivers 
  3. Buy all available tractor aerodynamics 
  4. Optimize cruise control and vehicle speed
  5. Keep equipment maintained
  6. Implement the right axle configuration
  7. Embrace low rolling resistance tires
  8. Provide tools to reduce idle time
  9. Build a culture of methodically choosing technologies. 

“Although a number of factors influence fuel economy, such as operating weight and speed,” reported ATRI, “overall fuel economy can still be expected to improve in future years as motor carriers replace their existing trucks with newer models.”

In order to maximize fuel economy, start with the basics of spec’ing your Class 8 vehicle to perform in the most efficient and cost effective way possible.