United Parcel Service just became Tesla's biggest Semi-truck customer to date.

The delivery service and logistics provider announced Tuesday morning its plans to preorder 125 of Tesla's new electric Semi tractors.

Previously, beverage and snacks behemoth PepsiCo had reserved 100 of the trucks, the largest-known order as of last week. Companies including , fleet operator , and food-service distribution company have also made reservations for the Semis.

"These groundbreaking electric tractors are poised to usher in a new era in improved safety, reduced environmental impact, and reduced cost of ownership," Juan Perez, UPS' chief information and engineering officer, said in a statement.

The new Tesla tractors will add to UPS' existing fleet of trucks, which are propelled by electricity, natural gas, propane, and other non-traditional fuels, the company said.

By working with Tesla and being one of the first companies with the new Semis on the road, UPS aims to reduce its absolute greenhouse gas (GHG) emissions as much as 12 percent by 2025, the company said.

Tesla, spearheaded by CEO Elon Musk, aims to win the trucking community over with an affordable electric big rig that comes with the range and cargo capacity to compete with lower-cost diesel vehicles.

With a slick design that will allow truckers to stand in the cab, Musk and his team have said the electric Semis will give drivers a much better experience, while improving safety and cutting costs. The California-based automaker unveiled the Semi last month and expects the truck to be in production by 2019.

Tesla shares were falling about 1 percent Tuesday morning, having climbed more than 55 percent in 2017.