Fuel is one of the most expensive regular costs that businesses have to deal with. The American Transportation Research Institute found that fuel costs were the second-highest cost to trucking fleets behind only driver wages, making up as much as 24% of regular operating costs. Fuel prices can be volatile and subject to sudden increases based on factors as unpredictable as international politics, the weather, or even cyber warfare. These factors make it difficult for fleets to predict their impact.
But while a spike in prices at the pump may be out of a fleet’s control, fleet managers can succeed in reducing the amount of fuel that their drivers use.
Fuel costs are the second-highest cost to trucking fleets behind only driver wages, making up as much as 24% of regular operating costs.
Aggressive Driving Reduces Fuel Efficiency
Driver behavior can have a considerable impact on fuel economy. For example, aggressive driving habits such as hard acceleration, late braking, and speeding are contributing factors in lowering a fleet’s fuel efficiency.
One study found that aggressive driving lowered fuel efficiency by 30% in urban environments when compared to calmer driving habits. There was less of an impact in highway driving, only 3%, but if a business relies on regular driving, fuel savings, even increment ones, can still help fleets get an edge on fuel costs.
The Science of Aggressive Driving
There are many reasons why aggressive driving can impact fuel economy. Some are mechanical and dependent on the type of vehicles your fleet runs. But other factors are strictly a matter of physics.
From heavy-duty trucks to light-duty delivery vans, fleets of all sizes and types tend to have the same factors working against them regarding fuel economy. For example, work vehicles are heavy when compared to their domestic counterparts. They also tend to be designed to make them efficient for their intended task, but not for sliding through the air.
A lot of engineering effort goes into reducing both factors, but at the end of the day, fleet vehicles will be heavy and large, and both of these elements will affect how much effort the engine has to exert to get them moving.
How Hard Acceleration Hurts Fuel Economy
Many drivers are in a hurry. They have tight schedules and quotas they need to meet. This makes the stop-start nature of driving in a congested urban environment much more susceptible to aggressive driving behaviors like hard acceleration.
A driver may think that by getting to the speed limit as quickly as possible that they will be wasting less time and potentially beating an upcoming light that would force them to come to a stop and repeat the fuel-wasting behavior all over again.
But accelerating from a stop is one of the most wasteful cycles for an engine, requiring the most effort to move a heavy object from a standstill with no help from momentum.
Every engine has a sweet spot called the power band, an RPM range where it produces the most power for the least amount of fuel. Beyond this range, there are diminishing returns which means the engine will generate less power and use more fuel.
Slower acceleration mitigates these effects by allowing the engine to build speed while spending more time in the optimal power band.
Late Braking Wastes Momentum
Another hallmark of aggressive driving is late braking. Whether on city streets with endless stoplights or in stop-and-go traffic, drivers in a hurry tend to want to waste as little time at a standstill as possible.
But late-braking also wastes an essential benefit of acceleration – momentum. Sir Issac Newton famously established that objects in motion tend to stay in motion. When applied to fleet vehicles, this means that once your truck or van is already moving, it’s going to take less effort to keep it moving.
By anticipating a stop earlier and allowing your car to coast and retain momentum for longer, there is a higher likelihood that the vehicle will not have to come to a complete stop before needing to accelerate again which saves fuel during the next acceleration cycle. It also extends the amount of time spent coasting, which lets the engine sip fuel while momentum does the hard work.
Lastly, using the engine to help slow down the vehicle reduces wear on brakes and puts the energy that would have been wasted into another essential task.
Speeding is About Diminishing Returns
In the same way that engines have a sweet spot for fuel-efficient power, vehicles also have a top speed of maximum efficiency. Oak Ridge National Laboratory found that this zone is between 35 mph and 50 mph for most vehicles.
Beyond 50 mph, another natural force, drag, becomes a greater hindrance to a vehicle. According to Oak Ridge, for every 10 mph above 50 mph, fuel economy is reduced by 12%. The problem gets worse at higher speeds, with MPG decreasing by 15% from 70-80 mph.
Driving at or below 50mph may not make sense for every situation, and as with all of the above driving habits, fleets must always balance efficiency with maximizing productivity. But it is helpful to remember that on shorter trips under 100 miles, a 10mph difference is likely only to net a few minutes of time saved. At higher speeds, the time savings only diminish while the hit to fuel economy increases.
Telematics Can Help Fleets Address Aggressive Driving
A telematics solution can be a useful tool in addressing aggressive driving behavior. Telematics can monitor driver behavior and show fleet managers when a driver is accelerating and braking too hard and if they speed too often.
Businesses can set the parameters they would like their drivers to follow and see how well the drivers are adhering to it. By changing a few common driver habits, fleets can work to improve the fuel efficiency of their fleet, reducing one of their major costs.
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.
“The Effect of Aggressive Driving on Vehicle Parameters” – Department of Automotive Engineering and Transport, Kielce University of Technology – https://www.mdpi.com/1996-1073/13/24/6675/pdf
Quantitative Effects of Acceleration Rate on Fuel Consumption – Environmental Protection Agency https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=9100WZVZ.TXT