Fleets can do a variety of things to control their freight efficiency. But one thing outside their control is weather especially wind and temperature. Both of those elements can impact how much fuel a truck consumes.

Headwinds and crosswinds reduce truck fuel economy by increasing aerodynamic drag. Drivers heading in an east-west direction are almost sure to run into crosswinds and headwinds. In fact most drivers will have to deal with wind of some sort because in the United States at any given time there is a 7-mile per hour wind in some direction.

It is believed that for every 10 mph of headwind or crosswind MPG is reduced by 13%.

We had firsthand experience with wind during the recent Run on Less cross-country road show. Henry Albert, one of the drivers in the Run, experienced both the good and bad about wind. During part of the three-week Run he was subjected to first headwinds and then tailwinds during hurricanes Harvey and Irma. Tailwinds gave Albert a 1.5 mpg boost in fuel economy.

Ambient temperature also has an impact on fuel economy. High temperatures affect tires by reducing rolling resistance. For every 10°F drop in temperature, aerodynamic drag increases by 2%. As a result, fuel efficiency will decrease 1%.  And the energy needs to cool a cab during hot summer nights increases over cooler winter ones.

Rain and snow too can cause fuel economy to suffer.  An SAE test found that rolling resistance and drivetrain friction in light rain increase fuel consumption by 0.2 to 0.3 MPG.

Since there are things fleets and drivers can’t control like wind, temperature and precipitation, the good ones concentrate on making improvements to things they can control like the way the truck is originally spec’d, additional fuel efficient technologies that are added to the truck and driving practices that help them get the most miles from each and every gallon of fuel.