SAN FRANCISCO – Big freight haulers want some tryout time with Tesla’s new semitrailer truck.

Orders are trickling in for the sleek vehicle, unveiled in mid-November. Last week, UPS said it wants 125. Also this month, PepsiCo ordered 100. Budweiser parent Anheuser-Busch reserved 40. Sysco, the big food distributor, wants 50. Walmart ordered 15.

That’s peanuts compared with the 940,000 heavy-duty semi trucks sold around the world each year, 238,000 of them in the U.S. — and the Tesla truck won’t be available until 2019 at the earliest.

But it’s a strong start for a new entry in the semi market. And it proves that major freight operators, intent on cutting costs without degrading service wherever possible, are taking the Tesla Semi seriously.

Efraim Levy, a stock analyst for CFRA, thinks Tesla’s stock is overpriced, but he said the orders “do show some corporate backing for the semi truck initiative.”

Trucking is anything but environmentally friendly. Current-generation semis get around 6 to 8 miles to the gallon. Diesel engines, like all internal combustion engines, spew fumes that contribute to global warming.

But it’s an essential industry: Trucks haul 70 percent of the freight in the United States. And if fleet owners can get the job done with significant cost-cutting while satisfying government clean air regulations, they’ll go electric, whether from Tesla or from somebody else.

“Heavy-duty customers buy from a spreadsheet,” said Mary Gustanski, chief technology officer of motor vehicle supplier Delphi Technologies. Cool looks might excite PepsiCo’s marketing department, but performance and efficiency are what would spread the Tesla Semi through the fleet.

The early fleet buyers will begin real-world testing after they buy their trucks. (Tesla said Semi deposits range from $5,000 to $20,000 and are refundable.) Much of the testing is likely to take place in Nevada: Tesla’s battery factory is there, Nevada state law encourages semi truck experimentation on public highways and freight distribution points dot the state in a way that makes a 300- to 500-mile range workable.

For example, Walmart runs a huge distribution center, one of its largest, in Sparks, Nev., right next door to Tesla’s Gigafactory. Tesla is certain to use the Tesla Semi to deliver batteries to the Fremont auto assembly plant. Rather than “deadhead” back with an empty load, those trucks could stop at the Port of Oakland and carry freight to Walmart in Sparks.

PepsiCo runs a big bottling plant in Las Vegas. Interstate 15 runs 420 miles to Salt Lake City, most of that through Nevada. It provides a real-world proving ground for Tesla’s truck, which the company claims can drive 500 miles before recharging.

When trucks roll between distribution points within that range, they can recharge while parked at fleet-managed lots overnight and get maintenance when they need it.

Fleets that work those kinds of routes are ideal for electric truck experimentation, said Greg Hirsch, senior vice president of trucking and logistics firm Daseke in Addison, Texas.

Daseke isn’t ready for electric trucks yet, Hirsch said. Its 5,200 trucks run long, irregular routes carrying heavy goods on flatbed trailers. There isn’t enough charging infrastructure yet, and no maintenance and repair network to support long-haul electric trucks.

But Hirsch said he’ll follow the tryouts closely. “It’s an interesting technology. We’re not early adopters. But anything that improves efficiency and safety, we want to jump on that as quickly as can be proven practical.”

Test-bedding in Nevada holds another advantage: The state is emerging as a driverless-truck testing zone.

In June, six months before the Tesla Semi was revealed, the Nevada Legislature passed a bill that requires human drivers present in autonomous trucks — but also allows the Nevada Department of Motor Vehicles to make exceptions and allow testing of trucks with no drivers.

Tesla hasn’t talked much about applying its Autopilot self-drive technology to trucks, but no one doubts the company will.

The Nevada law also allows truck platooning, in which lines of computer-controlled trucks drive closely enough behind each other to take advantage of aerodynamic drafting, like cyclists in a bike race. For now, human drivers are required for each truck in a platoon. Neither autonomous trucks nor platooning are allowed on California public roadways.

For the electric semi market to grow, coast-to-coast charging and maintenance networks must be built to satisfy long-haul truckers, who often travel more than 600 miles a day.