Tesla CEO Elon Musk confirmed on Sunday that the company is still working on a semi truck, a project first revealed in Musk’s July master plan — but it’s not exactly top of the priority list. Musk clarified on Twitter that the upcoming Model 3, the company’s $35,000 electric car, is currently taking priority over the semi, but that plans for the truck are still making progress.

The truck is part of Tesla’s plan to broaden its base and bring the technology it’s developed to a wider audience. The electric-driven vehicle will help revolutionize the cargo industry, as reduced fuel costs change the economics behind shipping.

“We believe the Tesla Semi will deliver a substantial reduction in the cost of cargo transport, while increasing safety and making it really fun to operate,” Musk said in the second master plan.

The Tesla Semi may change over time as the company develops its self-driving technology. In November, Musk suggested that truck drivers could eventually transition into “fleet managers” that oversee a range of self-driving trucks completing deliveries.

That vision is a while away, though. Musk estimates it will take around six billion miles of self-driving data before regulators are comfortable with the technology. At the time of the second master plan’s publication, Tesla cars were driving around three million miles per day through the semi-autonomous autopilot system.

“It’ll be a few years after trucks can self-drive before regulators have seen enough data to feel comfortable not having a driver in the car,” Musk said in the November interview with CNBC.

For now, it seems Musk is more keen to get the Model 3 out of the door. The conclusion to the company’s first master plan, the vehicle represents a long-term effort to bring electric car mass production down to affordable levels. The expected high shipping volumes have led to the company building the Gigafactory to keep up with battery demands.

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