Tesla unveiled its sign over the old NUMMI plant, where it will build the Model S electric car.

On Wednesday, Tesla CEO Elon Musk and California Senator Diane Feinstein stood before the New United Motor Manufacturing Inc. (NUMMI) plant, shuttered since April, and announced its new beginning as the base for Tesla Model S production. The press conference was capped by the unveiling of a large Tesla sign over the plant.

Tesla Vice President for Manufacturing Gilbert Passin conducted a tour through the parts of the factory that will host production lines for the Model S. Passin boasted that acquiring NUMMI was a huge cost savings for Tesla, as building a new plant would cost hundreds of millions of dollars. Toyota sold the plant to Tesla for $42 million.

See photos of the new Tesla factory.

Passin also pointed out that Tesla has been able to purchase equipment on site that will be useful for Model S production, ranging from simple carts all the way up to massive presses for stamping out steel body parts. As most body panels on the Model S will be aluminum, Tesla had to buy and transport a massive hydraulic press from a Detroit tier one automotive supplier.

Although NUMMI covers 5.5 million square feet, Tesla will only use about 20 percent of that space, mothballing the remaining 80 percent until it needs to expand production.

The south area of the facility, designated for the Model S assembly line, is mostly open space now. Passin and a crew of 70 Tesla employees on site are working to put in place the machines and processes that will be required for Model S production.

Tesla expects to start production of the Model S in 2012. The sleek four door premium sedan will have an all-electric drivetrain, a range of 300 miles, and seating for five adults, plus two children. It is the first car Tesla will be building from the ground up.