Medium-duty trucks, identified as Class 3-6, are the workhorses of the American economy. These vehicles deliver food and beverages to restaurants and convenience stores, drop off packages at homes and offices, serve as mobile workshops for all types of technicians, and perform thousands of other daily tasks. They also use a lot of fuel - more than 8 billion gallons per year. 

This fuel use represents a significant cost for the businesses that use these vehicles to deliver products and services. In addition, the combustion of fuel contributes to global warming.

By increasing truck fuel efficiency, companies can reduce costs and decrease carbon dioxide emissions - the main contributor to human-caused global warming. Medium-duty trucks emit an average of more than 13 metric tons of carbon dioxide per vehicle each year. Focusing on reducing these emissions - including ongoing emissions measurement - needs to be at the core of any comprehensive fleet "greening" effort.

Select Lower-Carbon Vehicles

The most important environmental decision a fleet manager makes is which vehicles to have in the fleet. Relatively minor changes in vehicle selection can result in significant environmental - and financial - benefits over time. Consider the following strategies when choosing fleet vehicles.

➧ Move to Lower GVW Trucks.

Lighter and less-powerful trucks are more fuel efficient. A company can reduce fuel use significantly by "right-sizing" its fleet - selecting trucks no larger or more powerful than necessary for the application. Avoid the common pitfalls of spec'ing the entire fleet based on a "greatest power demand" scenario, when such a scenario can be served with a few larger vehicles. Within the same gross vehicle weight class, it may be possible to choose a more efficient engine that can do the job at hand. (See Table 1).

➧ Consider High-Efficiency advanced technology vehicles.

Hybrid-electric vehicles, hydraulic hybrids, and electric vehicles all have the potential to increase the fuel efficiency of trucks and reduce emissions. Fuel-efficiency improvements between 15-50 percent are likely from these advanced technology engines. These vehicles are particularly well-suited for urban pickup and delivery and other short-haul markets. They are also a good fit for fleets with auxiliary power needs, such as utility trucks, which can draw power from the electric battery to run onboard equipment, eliminating idling and further increasing fuel savings.

The first commercially available medium-duty hybrid trucks hit the road in 2005 through a partnership between FedEx and Environmental Defense Fund (EDF). Today, more than 115 fleets contain medium- to-heavy-duty hybrid vehicles. Nearly 2,000 of these cleaner vehicles are on the road, available in more than 35 models and in every truck class. The performance and maintenance records of these vehicles are strong.

The most significant barrier to further expanding the market for these vehicles remains the upfront cost. Hybrid trucks typically cost between $23,000-$45,000 more than traditional trucks, but price differs between applications and models, while bulk purchases can help push the price toward the lower end of the spectrum. Still, for many applications, the trucks' payback is beyond the time limit of most companies.

To support the use of hybrid vehicles, the U.S. federal government and many states have funding available to help fleets purchase cleaner and more fuel-efficient vehicles. Grants, rebates, and tax credits can help bring down the incremental costs of advanced technologies and make the business case for cleaner trucks. Under the most generous of these programs, fleets can achieve a 2.5-year return on investment (ROI) from a hybrid truck.

Incentives may impact financing arrangements and as a result, the total financial benefits of the incentives need to be evaluated. Further, incentive programs can be complicated to navigate because their benefit may depend on a particular fleet's specific situation. However, the payoffs can be significant, so it is worthwhile for a fleet to do its homework and investigate these programs.

➧ Explore Lower-Carbon Fuels.

Not all fuels are created equal in terms of greenhouse gas (GHG) emissions. Diesel, gasoline, and other fuels all emit different amounts of carbon. Data on the carbon content of fuels is available from the U.S. EPA on a volume basis. For example, per gallon, gasoline emits more than 19 lbs. of carbon dioxide and diesel emits more than 22 lbs. Of course, other variables must be taken into account as well, such as the energy content of the fuel and engine efficiency. Consider that due to its higher energy content and more efficient combustion process, a diesel vehicle can travel about 30 percent farther on a gallon of fuel than a comparable gasoline model.

All fuels have emissions associated with their creation that aren't factored into EPA's tailpipe numbers. There are some fuels that have a lower GHG emissions profile when combusting the fuel, but this benefit is reduced or eliminated by an energy-intensive manufacturing process. Fleets seeking to reduce GHG footprints should do due diligence to ensure their fuel choices don't simply push emissions up the production chain.

Spec for Efficiency

Some vehicle components can be optimized to achieve better fuel efficiency and lower emissions. Many of the following options can work for both new and existing vehicles.

➧ Deploy Alternative Power Sources for Auxiliary Operations.

Alternative power for auxiliary operations can reduce fuel use. Examples include using electric motors instead of the truck engine to operate hydraulics on auto carriers and to power the operation of lift gates, as well as the use of cold plates in refrigeration units.

➧ Install Routing Software.

Vehicle tracking and routing software can monitor fleet operations and ensure vehicles use the most efficient routes and maintain schedules.

Fleets with dense multi-stop delivery networks are likely to benefit the most from software solutions to improve routing. Improved routing reduces unnecessary mileage, which also reduces fuel consumption. The level of fuel and emissions savings from this strategy will vary greatly depending on a fleet's operating characteristics.

➧ Reduce Vehicle Tare Weight.

By reducing the tare (empty) weight of a truck, fuel economy is improved. Less weight reduces both inertial loads and rolling resistance. Fuel economy savings can be particularly substantial in smaller truck classes because tare weight makes up a larger portion of gross vehicle weight. Tare weight can be reduced through the use of lightweight components, such as aluminum wheels and other body parts. The fuel economy improvement for each 1,000-lb. weight reduction in tare is shown in Table 2.

➧ Adjust Electronic Control Modules (ECM).

Electronic control modules (ECM) started to appear in vehicles during the 1980s. They are a class of onboard computers that include the engine control unit and transmission control unit. These computers help direct the management of the engine and transmission. Some ECMs can be modified to reduce fuel consumption by reducing top speeds, cutting idling, and lowering transmission RPMs.

● Install automatic engine shutdown.

Approximately 7 percent of all single-unit truck fuel use is associated with idling and this percentage is much higher for certain types of trucks. Fleet drivers who make frequent stops or wait in their vehicles for long periods may benefit from the use of idling-control technologies. Automatic engine shutdown can be programmed through the ECM. Trucks that lack an ECM-based shutdown capability can utilize available retrofit technologies.

● Make transmission adjustments.

The fuel efficiency of a truck is heavily influenced by the transmission and engine throttle operation. It is often possible to reprogram the automatic transmission control unit so trucks upshift at lower speeds. Factory settings for automatic transmissions are often based on maximizing power, not fuel economy. Of course, it is important to look closely at duty cycle to make sure the vehicle is not underpowered, which can be just as bad from a fuel and maintenance perspective.

● Limit vehicle speeds.

Speed reduction is one of the most effective strategies for improving fuel efficiency. Truck power requirements (and fuel use) tend to increase in an exponential manner above 40 mph, so limiting top highway speeds is a particularly effective way to save fuel. Many fleets choose to limit truck top speed to between 60-65 mph.

➧ Change to Low-rolling  Resistance Tires.

Tires have a direct impact on fuel economy. The amount of the impact depends on the rolling resistance of the tire model. A tire with lower-rolling resistance loses less energy in the consistent cycle of deformation and recovery as it rolls. According to the Transportation Research Board, reducing the average rolling resistance of tires 10 percent can equate to a 1 to 2 percent increase in fuel economy.

➧ Install Aerodynamic Improvements.

Aerodynamic resistance can be improved by lowering a vehicle's drag coefficient. All vehicles can benefit from a more aerodynamic cab design, which can include the design of the front bumper, grille, hood, and mirrors. For single-unit trucks with van-style bodies, there are additional potential benefits from improving the aerodynamics of the cargo space. Many aftermarket devices are designed for medium-duty trucks.

Engage Drivers in Reductions

How a vehicle is operated significantly affects fuel consumption and emissions. The drivers of company vehicles have a vital role to play in reaching corporate GHG emissions reduction goals.

➧ Inform Drivers about Fuel-Smart Driving Practices.

Smart driving habits decrease fuel consumption. Companies can inform drivers about these habits and provide clear guidance on their adoption. EPA lists a series of tips on optimizing fuel economy. A few high-impact ideas substantially under driver control are minimizing idling and avoiding aggressive driving behaviors, such as speeding and jackrabbit starts.

➧ Recognize Driver Performance.

Fleets that track vehicle performance by driver or vehicle can leverage the competitive instinct of their drivers. Consider openly ranking drivers by achieved mpg, idling time, or other criteria.

➧ Provide Drivers with Meaningful Incentives.

Fleets that can track vehicle-specific fuel consumption and mileage (or other relevant metrics) can provide drivers with performance incentives. These can be helpful because the financial benefits of saving fuel accrue to the company, not the driver. Consequently, sharing even some of the savings with drivers can have a positive impact on program results. Incentives must be meaningful enough to influence drivers, but not so substantial as to incite gaming. The actual rewards offered should reflect driver preferences and the organization's culture.

Track GHG Emissions

While implementing one or more of these strategies, it is important to understand the starting point. Successful fleet environmental management means actively measuring and reducing the fleet's GHG emissions over time.

➧ Create Fuel and Mileage Data Capture Systems.

Carbon dioxide emissions, the dominant GHG emitted from trucks, can be tracked from good fuel consumption data. Each fuel type has a volume-specific carbon dioxide coefficient. If current information on fleet fuel usage is not available, consider working with the fuel card provider to retrieve this data. Creating a good data capture system for fuel consumption is a necessary first step to managing emissions.

➧ Set a GHG Emissions Baseline.

To set an appropriate GHG baseline, companies should calculate emissions for the past several years. Although eventually a single year is selected as the baseline, it is important to look at the data from multiple years to identify unusual trends and ensure the right starting point is selected. The baseline year will be the year against which future progress is assessed. Therefore, don't select a year, for example, that had an unusually high or low amount of miles traveled, as it won't be a fair comparison for normal operating conditions.

➧ Consider Goals and Metrics for Tracking Emissions Reductions.

An emissions reduction goal can provide structure for a fleet "greening" effort and keep the focus on the ultimate desired outcome: lowering GHG emissions. When setting the goal, consider the variety of strategies available to reduce GHG emissions. Companies should set aggressive, but achievable reduction goals and timelines.

To track progress against the set goal, consider tracking other metrics in addition to total fleet GHG emissions. Some other possible metrics include: greenhouse gases per miles traveled, greenhouse gases per vehicle, and greenhouse gases per ton mile.

At least once each year, calculate fleet GHG emissions and compare progress via the chosen metrics. This data can also be used in public reporting programs such as EPA Climate Leaders, the Carbon Disclosure Project, and new carbon registries, which are of increasing interest to investors. It can also be included in the company's social responsibility or annual report.


The Road Ahead

Rising energy costs and climate change are long-term businesses challenges. They are particularly relevant to truck fleets, which consume a lot of fuel and are highly visible to customers and the general public. Fortunately, tools and technologies exist today that can get fleets started on the road towards a lower-emissions future.

Many of these tools and technologies have been highlighted. Of course, in the medium-duty truck realm, there is no such thing as a one-size-fits-all solution. Fleets successful in cutting emissions will be the ones that explore unique solutions for each of their distinct duty cycles, experiment with unconventional ideas, and exchange lessons learned with their peers.  

About the Authors
Jason Mathers is project manager of corporate partnerships for the Environmental Defense Fund. He can be reached at [email protected]. Karen Healey is the former director of product management at PHH. For more information, e-mail [email protected].