Drivers: Here’s How Your Behavior Affects your Diesel Truck's Fuel Economy
Your actions can affect how much fuel you use in surprising ways. Discover the four top habits of fuel-saving truckers.
Driver behaviors have a big impact on a truck’s fuel efficiency, even in advanced trucks with the latest automated transmissions for optimal gear selection. This was revealed by a recent North American Council for Freight Efficiency initiative called Run on Less, supported by Shell.
Here are five simple ways of improving your driver habits and lowering your carbon emissions:
1. Limit your top speed
Air resistance or drag increases with a 7 mpg = 0.1426 gpm vehicle’s speed. The rate of increased resistance can be significant. Doubling the speed increases the air resistance by a factor of four.
In fact, every 1 mph over 55 mph costs 0.1 – 0.2 mpg in fuel economy. That may sound insignificant, but consider a driver cruising at 60 mph and incurring a fuel economy penalty of 0.5 - 1.0mpg. For 10 trucks, each traveling 100,000 miles every year, the extra fuel cost could be over $127,000 – plus there’s the environmental cost.
Example Calculation Source: What is The Effect of Driver Behavior on Fuel Efficiency, White Paper by Shell, March 2020
2. Limit your RPM
For a given vehicle speed, lower engine revolutions per minute (RPM) use less fuel. Even with the highest quality, lowest viscosity lubricants, there’s always internal engine friction, which contributes to fuel consumption.
In general, engines operate more efficiently at high torques and low engine speeds (RPM). This means the fuel efficiency penalty of internal engine friction is lowest when the vehicle is operating in a high gear. A fuel-efficient driver tries to avoid high engine speeds and moves smoothly up through the gears as the vehicle speed is increased, ensuring the truck is operating in the highest reasonable gear at all times.
Braking converts the kinetic energy associated with the truck’s motion into heat, which is lost to the atmosphere. Instead of speeding up rapidly and braking sharply, fuel-efficiency conscious drivers anticipate the road conditions to enable them to change speed more smoothly, and thus reduce fuel consumption.
For example, rather than racing to a red light or queue of traffic, stopping sharply and then accelerating quickly away, they will see the red light or slowing traffic and reduce speed gradually. They may not have to stop if the lights change or the traffic starts to move before they get there.
Over time, smooth braking and acceleration help reduce wear on the tires and transmission.
3. Plan economically responsible routes
Often, the fastest journey is the most fuel efficient. But there are further potential gains from avoiding hills and making the most of long, straight stretches of road. The engine is under the most strain when accelerating, and up-hill driving is particularly fuel-thirsty work.
Route planning to avoid hills, minimize the time spent bringing the truck up to speed, and maximize cruising time is a sensible way to save fuel over a long journey.
4. Minimize idling
Truck driving is tough work, so modern vehicles come with powered-in-cab accessories, such as radios, air conditioning and phone chargers – vital for long journeys. Especially ones with overnight stops or in remote locations.
Power for these essentials is typically taken from the vehicle’s engine, which leads to higher fuel consumption. It’s common for engines to idle overnight, when it’s legal to do so, to keep in-cab accessories running to, for example, heat the cab while the driver sleeps. Some trucks have the option of using a small diesel engine or battery pack for auxiliary power to eliminate main-engine idling.
Driver behavior can help too. For example, cooling the cabin before stopping, or parking with the windshield facing away from the sun, can help lower energy costs during breaks.
Fuel-saving driver behaviors can easily be applied to good lubricant choices to maximize the benefits of both. The better lubricated a vehicle or piece of equipment is, the more efficiently it will run. The more efficiently it runs, the less fuel it consumes, and the lower its emissions.
Using a low viscosity lubricant can result in fuel savings of 1% to almost 3%, compared to ‘thicker’ SAE 15W-40 engine oils. Engine manufacturers have been factory-filling with lower viscosity engine oils to realize fuel economy savings since 2013, or even earlier in most cases.
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