Tesla Inc. (TSLA) faces a near impossible task to deliver on its semi-truck and Roadster sports car promises, various electric vehicle experts have warned.

Earlier this month, the company’s CEO Elon Musk wowed Wall Street by unveiling two new vehicles that defied all expectations. One of them was a battery-powered truck boasting 500 miles of range and the ability to add 400 miles of charge in as little as 30 minutes. (See also: Tesla Surprises With New Supercar at Semi Truck Unveiling.)

Bloomberg reports that the battery required to power the new semi would cost an estimated $100,000 based on current prices, leading it to question how Tesla could make any profit on the truck, especially as the company plans to sell it to consumers for $180,000.

Salim Morsy, electric vehicle analyst at Bloomberg New Energy Finance, also debated whether Tesla can feasibly meet its charging ambitions. The company said it plans to use a “new megacharger” to add 400 miles worth of juice in 30 minutes. Morsy believes that could be very difficult to achieve, noting that Tesla would need to build technology 10 times faster than its current best chargers to achieve its goal.

Colin McKerracher, head of advanced transport at Bloomberg New Energy Finance, agreed with this assessment: “The fastest chargers today can support up to around 450kW charging, so it’s not clear yet how Tesla will achieve their desired charging speeds,” he said, according to the Financial Times. “One option may be to segment the battery somehow and actually charge different segments simultaneously. This adds additional costs and we haven't seen anything like that done at anywhere near this power output.”

John Feddersen, chief executive of consultancy firm Aurora Energy Research, joined the raft of commentators arguing that Tesla’s plans for its electric hauling truck are perhaps over ambitious. According to his estimates, the company would require 1,600 kilowatts to recharge the semi’s battery in such a short timeframe. That, he told a London conference, is the same amount of energy needed to power up to 4,000 homes.

Analysts were equally skeptical about Tesla’s ability to deliver on its promises for the other vehicle it recently unveiled in Los Angeles. During the event, Musk described the new $200,000 Roadster as the quickest production car ever made and, perhaps even more ambitiously, claimed that it can cover 620 miles on a single charge.

To achieve that power and range, Musk said the Roadster will require a 200-kilowatt-hour battery, which is twice the size of the ones used to power the Model S and Model X. Bloomberg analyst Morsy noted that packing such a huge battery into a tiny car is currently impossible.

“I really don’t think the car you saw last week had the full 200 kilowatt hours in it,” Morsy said. “I don’t think it’s physically possible to do that right now.” (See also: Morgan Stanley Asks: Is Tesla Headed for a Fall?)

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