Tesla Motors is often frustratingly opaque about the company's progress in getting its 2012 Tesla Model S electric sport sedan up to mass production.

Hard numbers come only from quarterly reports filed with the SEC--and sporadic tweets from Elon Musk, its CEO.

According to one of those tweets yesterday, Tesla Motors [NSDQ:TSLA] built its 1,000th body shell for the Model S, presumably on or around Sunday, October 28.

Musk's tweet said the company had completed more Model S cars in October than in the entire rest of the year, from the start of production in May or June through the end of September.

The CEO included a photo of more than 100 Tesla factory workers gathered around the body, with a crude cardboard sign saying "We loaded 1,000" propped in front.

There appears to be no way for journalists to verify Musk's statement independently.

On September 15, Musk had tweeted, "Tesla made 100 vehiclebodies this week for the first time. Really proud of the team!"

Although Musk identified the body in that photo as serial number 396, the company's Christina Ra said the number of 400 bodies built was inaccurate.

She would not provide any information to back up this claim, beyond saying that the serial number was not indicative in this case.

Clearly, if 1,000 bodies have just been assembled, the number of finished cars that have been completed is lower, and the number delivered to customers lower than that.

Tesla has been slower to ramp up production of the Model S than it had planned.

Since June 22, when it delivered its first 2012 Model S cars to paying customers, it took six weeks for the company to reach a total of 50 cars built.

In late September, Tesla said in a statement filed with the SEC that it expects to sell only 2,700 to 3,225 cars by the end of the year, rather than the 5,000 it had previously forecast.

Still, if 1,000 bodies have been assembled, the company would seem to have a shot at meeting those revised targets if its production rate continues growing as it has to date.

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