One common goal among fleet managers is to reduce fuel spend by lowering engine idle times. Regardless of the industry or fleet segment, the issue of idling is widespread. “Researchers estimate that idling from heavy-duty and light-duty vehicles combined wastes about 6 billion gallons of fuel annually,” according to the U.S. Department of Energy.

Average national fuel prices have been on the rise as of late, making it even more critical for fleets to continually reduce this spend category as much as possible. Different fleet segments have different expectations and needs when it comes to idling and idle reduction. This complex issue should be assessed particular to its vertical.

Light-Duty Vehicle Idling Costs

Idle fuel consumption varies widely depending on the size of vehicle and fuel type. If your fleet operates lighter vehicles like sedans, gasoline powered compact sedans with 2-liter engines consume a little under 0.20 gallons of fuel per hour while larger sedans with 4.6-liter engines consume just under 0.40 gallons of fuel per hour, according to aggregated data compiled by the Argonne National Laboratory.

Compared to a medium-heavy truck with engine sizes between 5 liters and 7 liters, which burn more than 0.80 gallons of gas per hour, idling vehicles with smaller engines may not seem like a lot, and therefore not seem as necessary to address. However, take a fleet with issues of excessive idling that has at least two larger sedans and one compact sedan, and the fleet is already burning at least 1 gallon of fuel an hour, overall.

As an example, if these three vehicles idle one hour a day for a business that operates five days a week, and we factor in a national average of $3 per gallon of regular unleaded gasoline, you could be costing your business around $15 dollars a week. And if that remains the average for the entire year, the fleet may be wasting $780 in idling expenses.

But this example just considers a possible base minimum scenario. If your fleet is even slightly larger than this and has a more diverse vehicle portfolio, you’ll probably be spending much more. If we simply double the base example of two larger sedans and one compact sedan: now your fleet may be wasting $1,560 in fuel every year.

However, sometimes the weather makes some amount of idling necessary. For example, in winter, driver’s may need to idle vehicles in order to defrost their windows, according to the U.S. Department of Energy. To offset any otherwise incidental idling, turn off the engine, whenever appropriate, if the temperature is moderate. GPS tracking, including available solutions from GPS Trackit, can further help enable fleets to curb excessive fleet idling behaviors through driver monitoring.

“I decided to give it a try and I felt that I was given total control over knowing where my vehicles were, what they were doing along with fuel consumption which in turn saved me some money,” said GPS Trackit customer Peter G.

Medium-Duty Vehicle Idling Costs

Moving up in segments, fuel spend from idling increases as the vehicles and their engine sizes get larger. The medium-duty segment typically factors in utility, courier, and package delivery trucks.

A medium-heavy truck powered by gasoline and a diesel-powered delivery truck – both with a gross vehicle weight over 19,500 lbs. – each burns a little over 0.80 gallons of gas per hour when idled, according to aggregated data from the Argonne National Laboratory. This can create a staggering impact on fuel spend if we multiply this with a larger fleet size, compounded with current rising fuel prices for both gasoline and diesel fuel, according to the U.S. Energy Information Administration.

However, the factors related to idling become more nuanced when assets are introduced that require power take-off functions, which transmits power from a running vehicle engine and sends it to another piece of equipment or application.

Lets take, for instance, a loaded diesel bucket truck that is operating a crane with power take off to power its lift. An idling vehicle of this type uses roughly 1.50 gallons of fuel every hour, according to the Argonne National Laboratory. Even if the fleet only had four of these vehicles in operation that were idled for an hour a day, that would add up to 6 gallons of fuel per day.

Indeed, results from the 2015 Work Truck Electrification and Idle Management Study showed idling in excess of three or more hours was found more often in utility and telecom fleets, and saw occurrences of idling overall, so some idling excesses are expected here.
For those in these industries, with the means and capabilities to, the U.S. Department of Energy suggests the adoption of certain idle reduction technologies including auxiliary power systems, air heaters, automatic power management systems, and waste-heat recovery systems.

Heavy-Duty Truck Idling Costs

Fuel wasted while idling is also a major expense for the heavy trucking segments. Indeed, approximately 1 billion gallons of fuel are wasted in the U.S. annually from rest-period truck idling, according to Argonne National Laboratory. For long-haul truck drivers, after driving for 11 hours, they must have 10 hours off duty. Indeed, it is estimated that more than one million long-haul, heavy-duty trucks are idled during federally required rest periods every day, according to the Argonne National Laboratory.

“Surveys have found that 70 to 80 percent of truck drivers say the need for heating or air conditioning is the main reason they idle their trucks during their 10 hours off duty,” according to the U.S. Department of Transportation. Drivers also noted their idling derived from a need to operate on-board electrical appliances, such as a television or refrigerator, and to ensure the engine block, fuel, and oil remain warm.

For comparison sake with other segments, a fully-loaded class 8 semi-trailer – that is on high idle with its air conditioning on – has an idle fuel usage of 1.15 gallons of diesel fuel an hour, according to the Argonne National Laboratory.

If you have 14 vehicles of this type idling just for an hour a day, your fleet would be looking at burning a little over 16 gallons of diesel fuel in a single day. However, from this excess in idling, there’s also subsequently more maintenance costs as a result through increased engine wear.

Idling can be damaging to an engine and vehicle components, because idling can produce sulfuric acid, which can eat away at the engine and other components, according to the Oak Ridge National Laboratory. Idling also results in lower in-cylinder temperature combustion, which can produce additional soot, and creates buildup in the engine, among other issues. Additionally, idling can impact vehicle warranties, particularly when the manufacturer warranties and maintenance intervals apply to hours operated rather than miles traveled, according to the U.S. Department of Energy.

Planning and optimizing your fuel consumption is easier with a fleet management solution like GPS Trackit. If you’d like to learn more about how GPS Trackit can help you better maintain your fleet’s assets with GPS tracking and telematics, contact a Fleet Advisor to learn how to get started.

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