UPS has purchased 125 Workhorse E-Gen gasoline-electric hybrid step vans to reduce operating costs and save fuel, the Atlanta-based parcel delivery company announced. The E-Gen trucks will be replacing gasoline-powered vehicles.

The new trucks are expected to deliver up to four times the fuel economy of the gasoline-powered vehicles they are replacing. The new vehicles will be deployed in Arizona, Texas, Nevada, Mississippi, Alabama, Georgia, and Florida during the first half of 2016, according to UPS.

"These vehicles are a bridge to the delivery trucks of tomorrow," said Mark Wallace, senior vice president global engineering and sustainability.

The E-Gen includes a small internal combustion engine that serves as an on-board backup generator to recharge the vehicle's battery when the truck is in park. The vehicle features a 60-kilowatt lithium-ion battery pack containing Panasonic 18650 cells, and it offers a 50- to 60-mile-per-day range, according to Workhorse Group, the Cincinnati-based company that manufactures the E-Gen.

UPS purchased the trucks as part of its commitment to utilize advanced technologies to reduce the environmental impact of its fleet. While the new electric vehicles will cost UPS slightly more than a similar truck with a conventional engine, the company's sustainability commitment influenced the purchase decision, UPS added.

UPS is also collaborating with Workhorse to develop a more intelligent electric vehicle to determine when and where the batteries will be charged and re-charged.