Stop fleet engine idling to save fuel and reduce wear

Whether a driver is waiting for materials on a job site, leaving a truck running during a delivery, or running the engine just to keep the cab temperature comfortable, engine idling is an everyday occurrence for fleets.

While these idle moments may feel like a harmless necessity of the job, they actively inflate fuel budgets, degrade vehicle health and increase a fleet’s environmental footprint.

What is engine idling?

In simple terms, engine idling is running a vehicle's engine when it is not in motion. Some idling is just a part of regular driving, such as sitting in heavy traffic or waiting at a stoplight. However, a large portion of engine idling is elective — like leaving the truck running during a lunch break, a long phone call or while waiting on a job site.

Fleet management solutions measure these events by pulling data directly from the vehicle’s engine control module or ECM. By monitoring the "ignition on" status alongside a GPS speed of 0 mph, the system can accurately clock every stationary minute. This technology can even differentiate between wasteful engine idling and necessary engine use, such as when a truck’s engine must run to power a crane, pump, or lift via a power take-off unit.

Engine idling impacts on fuel efficiency, engine health and the environment 

The true cost of idling is felt in three primary areas: Immediate fuel expenditure, long-term mechanical degradation and regulatory or environmental risk.

Engine idling significantly reduces fuel economy

Fuel is often a fleet's second-largest expense,¹ and engine idling is essentially paying for zero miles of progress. Across the trucking industry, wasted fuel from engine idling translates into more than $11 billion annually, even when fuel prices are at a modest $2 per gallon.² 

Over a year, a typical long-haul truck may idle for 1,800 hours, burning through 1,500 gallons of diesel without ever leaving the curb.³ Assuming that same low cost of $2 per gallon, a single truck wastes $3,000 a year in engine idle hours.

The numbers get much worse as you scale fleet size. A mid-size fleet of 50 is essentially evaporating $150,000 every year just by sitting still. If fuel prices rise to $3.50 per gallon, that fleet cost jumps to $262,500.

Recapturing $150,000 in wasted fuel is just the first step toward a more profitable operation. For a broader look at turning idle data into growth, explore our guide: Optimizing Fleet Performance: Strategies for Maximizing ROI.

Engine idling increases engine wear and maintenance

While fuel waste is the most visible cost, the mechanical toll on the engine is often more expensive in the long run. Many drivers skeptically wonder: is idling bad for the engine?  But the research shows that engine idling is much worse for an engine than stopping and starting. Running an engine at no or low speeds causes twice the wear on internal parts compared to driving at regular speeds.⁴ When an engine idles, it puts on what’s called “ghost miles,” meaning your engine is more worn than indicated by mileage. In fact, if you want to convert engine idle hours to miles, a general rule of them is that one hour of idle time equals 25 to 30 miles of driving.

Download our eBook: 4 Ways Telematics Can Improve Fleet Maintenance to learn how to use engine hour data to protect your asset's lifespan.

Because an engine does not operate at its optimal temperature while idling, fuel is only partially combusted. This leads to a buildup of carbon residue on cylinder walls, which can contaminate oil and damage critical components like spark plugs and exhaust systems. This "dirty" combustion shortens the overall life of the engine and leads to more frequent, costly maintenance interventions.

Engine idling impacts the environmental and carries regulatory risk 

Beyond the vehicle itself, engine idling has a profound impact on air quality. While it may seem like a minor habit, the cumulative data is staggering. In the U.S. alone, heavy-duty truck idling consumes 1 billion gallons of fuel and emits 11 million tons of carbon dioxide every year.3 This isn’t just a waste of resources though. To put the impact in perspective, one hour of idling typically consumes about a gallon of fuel — the equivalent of five miles of driving — while releasing 55,000 tons of particulate matter into the atmosphere annually.3

There is a direct human cost.

Air pollution is a direct contributor to millions of deaths worldwide annually, and heavy-duty truck idling is a major contributor.⁵ According to the EPA, mobile source pollution accounts for over 50% of cancer risk related to outdoor air toxins and is a primary driver of asthma aggravation in the communities where trucks operate.⁶ 

Because of these engine idling impacts, local and state governments have implemented strict anti-idling regulations. Violating these laws can lead to significant fines, adding a layer of compliance risk to the existing financial burden of wasted fuel.

Download the 5 ways to reduce fuel costs eBook to learn how fleet management solutions can help you monitor the key factors contributing to wasted fuel.

The impact of seasonal and operational factors on engine idling

The urge to idle often fluctuates with the weather and the specific demands of the job site. Understanding these patterns is key to breaking the engine idle habit.

Weather-related idling

Winter weather presents a unique challenge for fleets. With hazardous driving conditions and freezing temperatures, drivers often idle to warm up the engine or maintain cabin comfort during long shifts. Statistics show that fuel economy in city driving is roughly 15% lower at 20°F than at 77°F, and can drop by as much as 33% on short trips.⁷

Many drivers believe modern engines need several minutes of idling to reach operating temperature. This is a carryover from the era of carburetors. Modern fuel-injected vehicles are designed to run efficiently almost immediately and are also increasingly equipped with automatic stop-start systems to mitigate some idling waste automatically. It is generally recommended to start driving gently after just 30 seconds of engine idling.⁸ This warms up all vehicle components, including the transmission and wheel bearings, much faster than idling the engine block alone.

Job site and delivery idling

Operational habits also contribute to the problem. Many drivers leave engines running during quick deliveries or while stationary at a job site to operate auxiliary equipment like pumps and cranes or keep climate control active. Without visibility into these stops, fleet managers often cannot distinguish between necessary engine use and avoidable waste. 

Many of these specific situations such as operation equipment or keeping cabin temperature comfortable can be solved with idle reduction technologies and fleet management solutions. 

Beyond these scenarios, engine idling is largely unnecessary. Even the myth that it wastes less fuel to idle than it does turn the vehicle off and on again isn’t true. Idling for as little as 10 seconds wastes more fuel than starting and stopping an engine.⁹ 

Effective strategies to reduce and mitigate engine idling

To manage engine idling, you first have to measure it. Fleet management solutions provide the objective data necessary to see where, when and why engines are running. They also provide additional support for ways to address engine idling with drivers, manage maintenance intervals better and improve routing.

• GPS fleet tracking: Identify every engine idling event across the fleet. Managers can set up customized alerts to receive a text or email notification when a vehicle idles beyond a specific threshold (for 5 or 10 minutes). Managers can also change settings based on geofenced areas where shorter or longer idling periods may be allowed.
• Driver coaching: Use engine idle reports to identify top offenders and provide coaching. Highlighting the benefits to the driver, such as a more reliable vehicle and a safer work environment, can help establish best practices early on. You may also understand why they idle and can address driver needs through other technologies or support.
• Maintenance and diagnostics: By tracking engine hours rather than just mileage, you can schedule preventive maintenance that more accurately reflects the actual wear on the vehicle. This helps identify precursors to mechanical failure, such as hard cornering or rapid acceleration, before they become major repairs.
• Routing and dispatching: Efficient routing reduces the time drivers spend sitting in traffic or waiting for their next job. Smarter dispatching allows managers to identify routes impacted by weather or congestion and direct drivers to more efficient alternatives, further reducing the opportunity for excessive idling.
• Power take-off integration: Utilizing a power take-off (PTO) unit with telematics allows fleet managers to differentiate between wasteful idling and necessary engine use, such as when a truck’s engine must run to power a crane, pump or lift. By capturing exactly when the PTO is engaged, you avoid penalizing drivers for real work time and ensure your engine idling reports only reflect truly avoidable fuel waste.

Additional engine idling reduction technologies

In those situations where drivers really do need to let their engines idle because they require power or climate control during rest periods, there are several technological alternatives to running the main engine called idling reduction technologies (IRT). These include:

• Auxiliary power units (APUs): These small, EPA-certified engines supply cooling, heating and electrical power without using the truck's primary fuel supply.
• Fuel-operated heaters (FOHs): Small heaters that burn a fraction of the fuel used by a main engine to keep the cab or engine block warm.
• Battery-powered systems: These systems use onboard batteries to power HVAC systems and electronics during rest periods.
• Thermal storage systems: These capture and store heat or "cold" generated during driving to be used later while the engine is off.
• Truck stop electrification (shore power): This allows drivers to plug into external power sources at rest stops, eliminating the need for any onboard engine use.

Real ways fleets reduced engine idling 

The impact of idling reduction is clearly demonstrated by fleets that have integrated telematics into their daily workflows.

• Sonoco Recycling: By using telematics to monitor engine idle time and optimize their routing, Sonoco saved over $100,000 in fuel costs. The ability to track engine use allowed them to maximize their route efficiency, increasing their average pickup from 12 tons to 18 tons per route.
• Olmsted Falls Police Department: Managing a fleet of police cruisers requires high availability, but frequent engine idling was draining their budget. By implementing Verizon Connect, they gained the visibility needed to monitor engine idle events across shifts, leading to significant fuel savings and a reduction in vehicle wear-and-tear. Supervisors no longer needed frequent one-on-one meetings to discuss engine idling practices — officers just know they’re in place and watching.
• KRP Rentals and Trucking: Operating in the demanding oil and gas industry, KRP used telematics to reduce engine idle times and improve dispatching. Though drivers would sometimes forget to shut the truck off or idle for other reasons, “with the new system, we're able to track those, and so we've had a lot fewer problems with the idle times. We've saved money on fuel costs,” KRP’s HSE director Kris Poole says.

Reducing engine idling is one of the most direct ways to improve the ROI of your fleet. By attacking the problem through a combination of telematics, driver coaching, maintenance scheduling and seasonal awareness with additional engine idling reduction technologies, you can significantly lower fuel bills, extend the lifespan of your vehicles and ensure your fleet is operating as sustainably as possible.

The engine idling report is just one of many fleet managers rely on to uncover efficiencies for their fleets. Learn more by booking a demo today.

Sources

¹ https://truckingresearch.org/2025/07/an-analysis-of-the-operational-costs-of-trucking-2025-update/ 

² https://afdc.energy.gov/conserve/idle-reduction-benefits

³ https://afdc.energy.gov/files/u/publication/hdv_idling_2015.pdf 

⁴ https://www.energy.gov/eere/vehicles/articles/fotw-1239-may-23-2022-idling-engine-little-10-seconds-will-use-more-fuel 

⁵ https://www.epa.gov/dera/school-bus-idle-reduction

⁶ https://www.epa.gov/mobile-source-pollution/research-health-effects-exposure-risk-mobile-source-pollution

⁷ https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health

⁸ https://www.energy.gov/energysaver/fuel-economy-cold-weather 

⁹ https://afdc.energy.gov/files/u/publication/idling_personal_vehicles.pdf