Here's one way Tesla managed to lower its cash burn that won’t last

SpaceX founder Elon Musk.
Joe Skipper | Reuters
SpaceX founder Elon Musk.

Nearly 30 percent of Tesla"s cash flow beat versus expectations for the December quarter is from an unsustainable driver: customer deposits for cars it hasn"t built yet.

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The electric-car maker posted a narrower-than-expected loss for its fourth quarter Wednesday. Tesla reported negative free cash flow (operating cash less capital expenditures) of $276.7 million versus its negative $1.4 billion in the previous quarter and the Wall Street consensus estimate of roughly negative $900 million.

Customer deposits rose by $167.8 million to $853.9 million in the December quarter versus $686.1 million in the September quarter, helping the free cash flow results. Analysts said the improving customer deposit figures are driven by its recently announced Tesla Semi truck and next generation Roadster.

Tesla shares declined 8.6 percent Thursday.

Evercore ISI said Tesla"s fourth-quarter cash flow performance had multiple one-time benefits.

"Investors will rightly question the quality and repeatability of the FCF development, with the improvements in inventory not repeatable, uncertainty around the sustainability of increasing customer deposits and benefits from [Zero Emission Vehicle] credits," analyst George Galliers wrote in a note to clients Thursday.

Tesla also implied that the customer deposit benefit may not occur in the future. The company was asked by an analyst about the drivers for the cash flow improvements in the quarter.

"Some of those are not repeatable. We significantly reduced the finished goods inventory of S and X in Q4, which will not repeat itself going forward. … Customer deposits may not be as well," Tesla"s chief financial officer, Deepak Ahuja, said on the earnings call Wednesday.

Tesla did not immediately respond to a request for comment.

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SpaceX just launched its most powerful rocket ever    6:59 PM ET Tue, 6 Feb 2018 | 01:18