The heads of Tesla Motors Inc. and Toyota Motor Corp. surprised the auto world May 20 by announcing a partnership to develop and build electric vehicles at a recently shuttered auto plant in the San Francisco Bay area.

Toyota President Akio Toyoda said his company will invest $50 million in Tesla when the company begins selling stock to the public, and Tesla CEO Elon Musk said his company will purchase New United Motor Manufacturing Inc., known as NUMMI, in Fremont, California, where the Model S electric sedan will be built.

"It's a great honor to work with a company like Toyota, one of the automobile leaders of the world and one I've personally long admired," Musk said at a news conference at Tesla's office in Palo Alto, California.

Kyodo News