FedEx Corp. has added 92 hybrid-electric trucks to its delivery fleet, bringing its total number of hybrids to 264.

The hybrid conversions were manufactured in Charlotte, N.C., with the help of Freightliner Custom Chassis Corp. and Eaton, which provided the hybrid-electric system. The trucks used in the retrofit were 2000 or 2001 models with 300,000 to 500,000 miles on them.

"The conversion of these standard FedEx trucks into hybrids is the latest milestone in our drive to advance and adopt hybrid technology into our fleet and the broader industry," said John Formisano, vice president of global vehicles at FedEx Express. "FedEx and our suppliers have demonstrated that converted hybrids are a viable, lower-cost option compared to purchasing new hybrids."

The switch is part of a larger, company-wide initiative to lower emissions. FedEx's hybrid fleet has logged more than 4 million miles of service since the introduction in 2004. The effort has cut fuel use by 150,000 and carbon dioxide emissions by 1,521 metric tons. The new retrofit hybrid trucks are expected to improve fuel economy by 44 percent, decrease particulate matter by 96 percent and reduce smog-causing emissions by 75 percent compared to the standard FedEx Express delivery truck.

"Hybrid technology helps FedEx reduce emissions and fuel use as we work to increase the efficiency of our vehicle fleet," said Mitch Jackson, director of environmental affairs and sustainability at FedEx. "We are eager for additional government and industry support to find more affordable options for hybrid trucks, so that we may adopt them into our fleet at a faster pace."

The new hybrid vehicles will be used in California, primarily in the Los Angeles, San Diego and San Francisco metropolitan areas.