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Tesla has said it will fully unveil its electric freight hauler this September, and Musk offered little new information about the vehicle beyond the picture. He did say he’d driven it, and described it as a “spry” vehicle. That’s not surprising, since the same torque advantages that make Tesla’s sedans more nimble than gas-powered cars scale up fairly well.

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Consider, for example, another large-format electric vehicle already on the road around the country—ProTerra’s Catalyst electric bus. That forty-foot vehicle has better acceleration than any diesel bus. (ProTerra is headed by Ryan Popple, a Tesla alum).

On the other hand, semis are generally carrying a heavier load than buses, and operate at a high, steady speed rather than stopping and starting a lot. There are real questions as to how that role will square with the need to recharge an electric truck as often as every four or five hours.

The semi is part of Tesla’s long-term ‘Master Plan,’ unveiled last year, which outlined electric vehicles filling a variety of niches, including pickups and vans, as well as integrated solar and battery systems to power them sustainably. On that broader agenda, Musk also slightly amended previous statements to say that the locations of four new Gigafactory battery plants would be revealed this year.

Musk also said that by the end of 2017, Tesla will fulfill its longstanding promise to send a car across the country fully autonomously. “November or December of this year, we should be able to go from a parking lot in California to a parking lot in New York, no controls touched at any point during the entire journey.”

During the same event, Musk also unveiled an arresting new concept video for The Boring Company. That nascent side-project aims to make underground tunneling cheap enough to build a network of high-speed sleds that would zip cars around at over 120 miles per hour.