Toyota Motor Corp. and its Silicon Valley partner, Tesla Motors Inc., will develop an electric version of Toyota’s RAV4 SUV, reported The Detroit News.

The two companies will work on prototypes combining the popular RAV4 with a Tesla electric powertrain. They expect to sell the SUVs in the United States in 2012, the two companies said.

A first prototype already has been produced.

“Tesla’s goal is to produce increasingly affordable electric cars for mainstream buyers — relentlessly driving down the cost of EVs,” the Palo Alto-based firm said in a statement.

Tesla now sells an electric roadster priced at just over $100,000, while Toyota is a leader in gas-electric hybrid vehicles. It has said it was planning to start selling electric cars in the United States in 2012.

The two companies announced in May that they would team up to develop electric cars.

Toyota invested $50 million in Tesla, in a side deal to the firm’s initial public offering. Tesla bought a factory in Fremont, near San Francisco, where Toyota and General Motors Co. had produced vehicles in the joint North American Motor Manufacturing Inc. venture for 25 years until its closure this year.

Tesla did not say where the electric RAV4 SUVs will be assembled, but the prototypes are being built at its facilities.

Electric-car maker Tesla Motors Inc. generated the second-best initial public offering gain of the year Tuesday, even as the broader market fell sharply, The Wall Street Journal.

Tesla’s ability to rise 41 percent against a backdrop of plummeting stock indexes wasn’t the only sign of high demand for the initial public offering. It also bucked a trend of new companies cutting the prices of their IPOs in the past several months amid stock-market volatility, and was able to sell its shares at a level above its expected range. Some IPO hopefuls haven’t been able to complete their deals and have shelved them for the time being.

Tesla’s IPO was expected to appeal to both clean-energy investors and car geeks, but its strong first-day showing isn’t an indication that all new stocks will be embraced as warmly. Earlier this month, another highly anticipated IPO from options exchange CBOE Holdings Inc. priced well and gained 12 percent on its debut, but the group of new issues that followed in its wake had mixed results in pricing and trading.

Tesla closed at $23.89 on the Nasdaq, up $6.89 from its IPO price of $17. Its 41 percent gain was the second-best debut from an IPO in the U.S. this year, behind the nearly 44 percent pop that Financial Engines Inc. experienced in March.

Tesla sold 13.3 million shares at a price above its expected range of $14 to $16. The size of the deal was also boosted Monday, with Tesla selling 11.1 million shares and current owners offering the rest. Among the sellers were Chief Executive Elon Musk, whose stake will fall from 36 percent to as little as 28 percent after the IPO.

The company, named for scientist and inventor Nikola Tesla, has been selling its all-electric Roadsters for nearly two years and is still the only company selling highway-capable electric vehicles to consumers in volume.