The Tesla Semi electric truck has started rolling off the high-volume assembly line, the American company said in a social media post on X. It's a big moment for the Semi, which debuted in 2017 as a potential game-changing heavy-duty hauler, but was ultimately plagued by countless delays.

So far, Tesla has built a few hundred Semis, according to Dan Priestley, Semi Program Director, but those vehicles were assembled on a low-volume line. Now, the company's factory in Nevada will ramp up production, with Priestley claiming during an episode of Jay Leno's Garage that the "economics are right" and that there is "ample demand."

The Semi, along with the Cybercab robotaxi and Megapack 3 stationary battery storage system, sits front and center in Tesla's spending plan. In January, the Elon Musk-led company said it planned to more than double capital spending this year to over $20 billion, primarily on the Semi factory, the Cybercab, the Optimus robot, and battery and lithium production.

Unveiled in 2017, the Tesla Semi promised to bring emissions-free hauling to the trucking industry. After building over 100 units that have amassed over 13.5 million miles on America's roads, Tesla updated the Semi last year, giving it a Model Y-like face and improving its efficiency.

Now, the electric big rig is available in two versions: a Standard Range model that delivers 325 miles at a fully-loaded weight of 82,000 pounds, and a Long Range version that's advertised for 500 miles. Both variants get a three-motor powertrain that can deliver up to 800 kilowatts, and an electric power take-off (ePTO) that can output up to 25 kW.

Charging can be done at up to 1.2 megawatts through an MCS 3.2 connector, allowing it to replenish 60% of its range in roughly 30 minutes. Efficiency, meanwhile, is where the Semi shines, with a Tesla-estimated 1.7 miles/kilowatt-hour. The company didn't say what the battery capacities are, but some napkin math suggests that the Standard Range model packs around 550 kWh, while the Long Range version has around 875 kWh.

During the same Jay Leno's Garage episode from March, Dan Priestley said that the batteries in the Semi are designed to last a million miles in their original duty cycle.

Inside, Tesla's electric truck offers a central seating position, flanked by two big touchscreens. A second seat is in the rear of the cab, but there are no airbags because of U.S. regulations.

With mass production now underway, Tesla says deliveries of the Semi will begin later this year.