Aaron Huff is technology editor of Commercial Carrier Journal. E-mail ahuff@randallpub.com

The bigger your expense, the faster small savings accumulate. With fuel being most fleets’ largest controllable expense, fuel optimization systems are growing in popularity. Such programs determine the lowest fueling cost alternative for each trip. When combined with operations software and mobile communications, fuel optimization becomes an almost automated process.

A vehicle’s beginning fuel level is one of the variables that a fuel optimization system considers. Unlike other variables, such as prices and consumption rate, the beginning fuel level is prone to human error, says Ben Murphy, vice president and general manager of Plano, Texas-based Integrated Decision Support Corp. (IDSC).

Fleets using IDSC’s Expert Fuel optimization software, for example, have drivers input their fuel level through their onboard communications systems once they have delivered loads. A macro prompts them to enter fuel level in eighths, Murphy says. Other systems, such as Prophesy’s FuelLogic, handle fuel level similarly.

When entering his fuel level, suppose a driver underestimates by 25 gallons. Assuming an average fuel consumption of 6 mpg, the optimization system would not factor an additional 150 additional drivable miles. While that variance hardly defeats the benefits of optimization, it does mean that optimization isn’t, well, optimized.

One way to remove human error from a fuel optimization system is with “smart” fuel-level sensors. A truck’s existing mechanical fuel sensors measure the fuel level roughly in terms of fractions of a tank. Janesville, Wis.-based SSI Technologies says a sensor it developed

The Acu-Trac sensor uses ultrasonic waves to calculate the actual quantity of fuel in tanks.