As prototypes of the Tesla Semi continue testing, the company is getting more feedback. And it appears that the range-topping version of the electric truck will have a better range than initially announced.

How much range? That would be close to 600 miles (966 km), as Elon Musk announced recently during the automaker’s Q1 2018 conference call, Electrek reports.

The Tesla founder’s statement, preceded by a good laugh, comes as an answer to Martin Daum, Daimler’s chief of the truck division, who said: “Tesla Semi defies laws of physics and is passing us by if true”, referring to the rig’s ability to travel for up to 500 miles (800 km) in between charges at full capacity.

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“If Tesla really delivers on this promise, we’ll obviously buy two trucks – one to take it apart and one to test because, if that happens, something has passed us by. But for now, the same laws of physics apply in Germany and California”, Daum added.

This is the range-topping version of the Tesla Semi, which is estimated to start at $180,000. However, the California-based firm will also offer a lesser model, with a 300-mile (480 km) range. This one is believed to shave approximately $30,000 from the top version’s asking price.

Tesla will commence production of the electric truck next year, if it all goes according to plan (admittedly, not something the automaker has a great track record at), and the first units will be shipped to customers in 2020.