In public, executives at Tesla Motors, Silicon Valley's highest-profile green-technology startup, are saying there's nothing wrong with their all-electric cars. In private, though, CEO Elon Musk has chastised employees to make vehicles that work.

Musk recently sent this email to employees:

Just a quick note to emphasize the importance of quality in the Roadsters that are being delivered to customers. This takes precedence over future developments.

Happy holidays,

What's Musk referring to? Surely it's the firestorm of criticism Tesla has faced after its $109,000 Roadster, a battery-powered vehicle whose all-electric motor makes for a thrilling ride, apparently ran out of juice on camera during a test drive by Top Gear, a well-known British automotive TV show.

A Top Gear spokeswoman later admitted the scene where the Tesla was pushed into the garage was staged, and it wasn't actually out of power. But the Top Gear show did highlight problems with the car, like brakes which unexpectedly died. Could that be what prompted Musk's holiday missive?

The notion that Tesla needs to fix its current line of high-end sports cars, rather than work on "future developments," is harrowing for a company which nearly ran out of money earlier this year and is seeking a $400 million loan from the government. Tesla's main "future development" is a mass-market sedan, on which the whole premise of the company is based; the Roadster is a showy way to enter the market, not the company's real mission, Musk has said. But if Tesla engineers can't make the Roadster work, why should taxpayers loan it money for a second car that even its CEO says isn't a priority?