Getting Better Fuel Economy

With continually rising fuel costs, the trucking industry faces yet another hurdle in maintaining profitability. Several mysterious factors dictate what price you will pay at the pump, but the bottom line is that it is not getting cheaper any time soon. One of the factors is where in the country you are purchasing fuel. California typically has been more expensive than other states.

So what kinds of things can a motor carrier and driver do to conserve fuel? Well, let’s start with the forces that negatively impact fuel economy.

  • Rolling resistance is a combination of tire design, construction, alignment, and proper air pressure. Drivers can help themselves by ensuring proper air pressure is maintained. Get training for your drivers now!
  • Aerodynamic drag is caused by three main factors, which are speed, coefficient of drag, and frontal area. The driver can only control speed. Aerodynamic devices that extend no more than 5 feet beyond the rear of the vehicle are conditionally exempt from a vehicle's length calculation by the Federal Highway Administration (FHWA).
  • Acceleration is the major user of energy. Drivers can control how quickly they accelerate.
  • Idling is also a major factor in fuel economy and is easy to cure. Drivers should shut down whenever they can. Several states are writing or currently have legislation in place prohibiting idling beyond 3-5 minutes.

Rolling resistance can decrease fuel economy by 3 to 5 percent. A tire that is 20 psi low on air can cause a loss in fuel economy of about 3 percent. Having tires that are out of alignment can contribute to the problem, too. Each axle that is out of alignment compounds the problem further. The easiest thing a driver can do to solve these issues is to keep all tires at proper inflation and check for uneven wear, indicating an alignment problem.

Aerodynamic drag reduces fuel economy by forcing the engine to work harder to maintain a certain speed. Large conventional-cab trucks have more drag than the new aerodynamic models being offered. Having a large gap between the tractor and the trailer also causes drag.

Speed however, plays the most important role in aerodynamic drag. Drag increases exponentially with speed, meaning that if you are traveling 65 mph, your drag is 40 percent greater than if you were going 55 mph, even though you are going only 18 percent faster. Studies have shown that traveling 65 mph rather than 55 mph only adds 5 to 8 mph onto the average speed but consumes 18 percent more fuel. Drivers should be mindful of their speed and slow down whenever feasible. Setting the cruise control is one tool that can greatly aid in increasing fuel economy.

Acceleration consumes energy. Accelerating smoothly and using progressive shifting can help the engine work easier, thus reducing fuel consumption.

Idling seems to be a sore subject with some drivers, but the reality of it is that idling uses fuel and shortens service life of the engine. Idling is necessary when temperatures are at the extremes, but when you drive through a truck stop on a beautiful fall evening with the temperatures around 65, you will still see the majority of trucks idling. To aid in cutting expenses, some companies are installing auxiliary power units to provide temperature control and electrical power. Using industry averages, most tractors consume slightly more than a gallon of fuel an hour at idle, which equates to approximately $5,000 worth of fuel annually. Combine that with savings from the other areas mentioned, and that can add up to a significant amount of money.

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