Tesla has officially completed its $42 million acquisition of the former NUMMI factory, a joint venture between Toyota and General Motors that was shut down in April due to the recession.

The New United Motor Manufacturing Inc. facilities in Fremont, Calif. spans 5.5 million square feet and will have to be refitted for production of Tesla’s Model S sedan (pictured below), which is slated to begin in 2012. The new factory marks the company shifting gears to focus entirely on Model S — it will cease production of the Roadster in 2011, though supplies are expected to last through 2012.

The process of retooling the factory has been in the works for some months now, said Tesla spokeswoman Khobi Brooklyn. Workers have been bringing in and installing new equipment, and Tesla is looking to hire and train 500 new workers, a process Brooklyn said is likely to continue into 2011.

Though there’s no set timeline for when the factory will go into production and all of the preparation work will be completed, Tesla will be holding a factory unveiling for press and invited guests on Oct. 27, which CEO Elon Musk will attend.

“We’re continuing to move equipment in, and that will keep going for many months,” Brooklyn said. “We’re really in the initial phase of this.”

Tesla has a Palo Alto manufacturing facility (pictured) that makes battery and motor packs specifically for the Roadster, but the company is refocusing on production and sale of the Model S, an all-electric sedan that has more mass appeal than the Roadster, a racy sports car that costs upwards of $100,000.

Tesla Model S Sedan

Tesla Model S Sedan

The Model S, on the other hand, seats seven, has a 160-, 230- or 300-mile range (depending on the battery pack option) and starts at $49,000 after a $7,500 federal tax credit. The company is taking reservations, which require a refundable fee of $5,000.

“The Model S is the premium sedan evolved. It will raise the bar of vehicle efficiency, meet the highest standards for safety, and provide more cargo space than any other sedan,” wrote Gilbert Passin, Tesla’s vice president of manufacturing, in a blog post detailing the manufacturing process for the sedan.

Car and Driver previously reported the Model S would go into production in the third quarter of 2011, and the company plans to produce them at 20,000 cars a year.

Tesla also previously purchased $15 million in factory equipment from Toyota.

[NOTE: At the official ribbon-cutting ceremony for the Fremont factory, Tesla CEO Elon Musk--among other things--compared plug-in hybrid vehicles to frogs.]

This story, written by Iris Kuo, was originally posted on VentureBeat's GreenBeat, an editorial partner of AllCarsElectric.