United Parcel Service announced it has places a reservation for 125 Tesla Semi tractors, making it the largest known order for the electric rig so far.

The package delivery company placed the order as it expands its fleet of alternative-fuel vehicles.

UPS has provided Tesla with their own real-world trucking lane information as part of the company’s evaluation of the truck’s expected performance under the UPS duty cycle. This is a common practice for UPS as they frequently partner with innovative vehicle suppliers to help them prepare their cars for the company’s specific needs.

“For more than a century, UPS has led the industry in testing and implementing new technologies for more efficient fleet operations. We look forward to expanding further our commitment to fleet excellence with Tesla,” said Juan Perez, chief information and engineering officer. “These groundbreaking electric tractors are poised to usher in a new era in improved safety, reduced environmental impact, and reduced cost of ownership.”

UPS’ alternative fuel fleet is currently including vehicles powered by electricity, natural gas, propane and other non-traditional fuels. Prior to this order, Tesla’s largest known single pre-order came from PepsiCo, which reserved 100 trucks.

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