In 2005, Walmart set a goal of doubling the fuel efficiency of its truck fleet to 13 mpg by 2015, according to widely published reports. By 2008, Walmart got its mpg up to 7.1 from 5.9 in 2005.

The fuel economy improvement was achieved with enhanced tractor aerodynamics, trailer skirts and spec'ing its trucks with equipment designed to save fuel, such as lighter tag axles, wide-based single tires and auxiliary power units, the company said in published reports. In 2008, Walmart added more than 1,100 aerodynamic trucks to its fleet, with plans to add 1,300 more in 2009.

When contacted for an update, Walmart officials told us the goal was to double fleet efficiency from 2005 through the end of 2010, rather than an mpg goal. The company's calculating this by dividing the number of miles traveled by the average fuel efficiency, measured in mpg. Then, the number of cases delivered during the same time period is divided by the amount of fuel used to deliver the cases.

So far, the company has achieved a 60 percent increase in fleet efficiency and continues to work toward that goal this year. Including all carriers, the company said 77 million more cases were delivered in 2009 than 2008, eliminating more than 100 million miles.

The company says it's been loading its trucks and cases more efficiently, improving routing and reducing the number of empty miles its trucks traveled. Fuel-saving technologies, such as improved engine calibration, have also helped.

The company is also making an effort to use trucks that run on alternative fuels. A full-propulsion ArvinMeritor hybrid is being tested in the Detroit area. The vehicle can operate on electric power below 48 mph.

Fifteen trucks operating out of the Phoenix area have been converted to run on reclaimed grease fuel, which is made from waste brown cooking grease collected at Walmart stores. Other trucks at the Phoenix center will use an up to 80/20 blend of biodiesel made of reclaimed yellow waste grease.

Walmart has five Peterbilt Model 386 heavy-duty hybrid trucks with diesel-electric hybrid power assist systems operating in Dallas, Houston, Atlanta, Baltimore and Apple Valley, Calif. These hybrid power assist systems were developed by Eaton and Paccar. Through a partnership with the Mojave Air Quality Management District, Walmart has four Peterbilt Model 386 trucks and one yard truck fueled by liquid natural gas.

"In order to meet our goal of doubling our fleet efficiency, we are taking an active role in the development of these technologies," says Chris Sultemeier, senior vice president of transportation. "We look forward to determining if these technologies will help reduce our environmental footprint, are viable for our business and provide a return on investment."

From the June 2010 issue of Heavy Duty Trucking.