According to an Elon Musk tweet on Sunday, it appears that Tesla has completed its 1,000th Model S body, and while this is not by any means a completed car, it does illustrate that mass production of the Model S is truly underway for Tesla.
"V proud of Tesla team for completing 1000th Model S body. More cars made this month than entire rest of year."
Tesla had expected to sell 5,000 vehicle by year's end, but later reduced that number to as low as 2,700 in a SEC filing in September. Sunday's news would indicate the company has a legitimate shot at achieving that goal.