Tesla is putting its new electric Semi to work, with its first run as a "production" vehicle -- for a familiar client. Tesla itself is the customer, as the trucks were equipped with trailers loaded up with battery packs fresh from the Gigafactory assembly line, heading to the Tesla Fremont car factory in California.
Elon Musk shared an image of the trucks at work, with both the matte black version and the silver one with the aero hood, which presumably are the same they showed off at the official unveil (they're the same color, at least). The trucks had full-size trailers attached, which is not what they've been equipped with during previous sightings.
The trip from the Gigafactory to the Fremont factory is around a four-and-a-half hour journey, covering around 260 to 270 miles. It's not exactly a long haul, but it could be something that's still very useful to a large number of customers, and it's a trip that Tesla itself has to make regularly with its own transport fleet for this very purpose.
Tesla calls this a "production" run, but its target for actually producing these still seems to be 2019, with a likely delivery time frame more like 2020. Still, this cargo run should provide valuable info to the company as it moves ahead, especially now that it has a sizable backlog of customer pre-orders to deal with.