General Motors’ board of directors has voted to start exploratory discussions with Nissan and Renault on a potential business alliance — a plan first proposed one week ago by Kirk Kerkorian, GM’s largest shareholder. But would a deal with the automakers help boost GM’s flagging fortunes?

GM announced Friday that its board has authorized the company’s management to consider and “weigh the potential benefits of such an alliance in order to assist the board in its decision making.�? GM Chairman and Chief Executive Rick Wagoner will lead the talks.

Kerkorian and his Tracinda Corp. first proposed that the U.S. automotive giant join in a business alliance with Nissan and Renault last week, pushing for GM to consider a partnership in an effort to help the world’s biggest automaker stage a turnaround and reverse its declining market share.

Kerkorian’s original proposal may have been little more than a shot across the bow of GM’s management, but it certainly increases the pressure on CEO Wagoner to hurry and fix the company’s internal problems according to John Casesa, automotive analyst and managing partner of Casesa Strategic Advisers.

“This ratchets up the pressure to accelerate change at this company,�? Casesa told CNBC in an interview last week. “There may never be a deal with Renault. … It may just catalyze internal change [at GM], and that’s what this shareholder is doing.�?

“Time is of the essence at GM, and the longer market share goes down, the weaker this company is going to be and the less valuable it’s going to be to a potential suitor,�? he said.

Talk of a three-way alliance already is paying short-term dividends for the Detroit carmaker. GM shares soared the day news broke that Kerkorian said Renault and Nissan were interested in including GM in their alliance. And they rose again Friday after GM said its board had approved exploratory discussions with Nissan and Renault.

The deal being proposed would involve Nissan and Renault, which are closely allied, each buying a 10 percent stake in GM. Even so, a deal would rank among the industry’s most significant of recent years along with the 1998 union of Daimler-Benz and Chrysler, and the business alliance of Renault and Nissan in 1999.

A partnership, which could bring GM a cash injection of $3 billion or more, could prove helpful in an increasingly competitive global environment, in which Japan’s Toyota is rapidly ascending and could soon eclipse GM as the world’s biggest automaker, Casesa said.

“I think Rick Wagoner and GM management has to ask itself this question: Is our mission to grow globally, and if it is, are we better together with a partner like Renault-Nissan, or are we better apart?�? Casesa said. “I think the answer is yes, it’s better to grow together, and that would be a reason for GM to consider this alliance.�?

While GM leads the world automotive market with a 14.2 percent share, its supremacy is under threat from Japan’s Toyota, which has a 13.8 percent market share. The combination of GM, Renault and Nissan would have a world market share of 23.7 percent, according to numbers from automotive forecasting company CSM Worldwide, leaving Toyota a distant second runner.

The main advantage to a three-way alliance among GM, Renault and Nissan would be the ability to merge some of their manufacturing processes, notes Kevin Reale, an automotive analyst at Boston-based AMR Research.

“From an overall cost leverage perspective, these three companies can share components across their manufacturing platforms and brands like never before,�? Reale said. “Both companies have huge global supply networks, plus GM gets access to the innovation we’ve seen at Nissan in the last few years — one thing we’ve seen at Nissan is an ability to sense market demand for a product.�?

Another advantage would be the inclusion of Carlos Ghosn. Nicknamed “The Icebreaker,�? Ghosn was dispatched by Renault to lead Nissan in 1999 and is largely credited with turning around its fortunes. The Brazilian-born Ghosn engineered a cost-cutting and morale-boosting campaign that revived the automaker.

Carlos Ghosn, the chief executive of both Renault and Nissan, has discussed the matter with Kerkorian and is willing to talk to GM according to a separate statement by Nissan and Renault. His turnaround expertise would be even more valuable than the cash infusion, Reale said.

Reale noted that on average Nissan makes $2,200 in pre-tax profit from each of its cars, while GM’s health care and pension liabilities mean it loses $2,490 per vehicle sold, or about $500 when those liabilities are stripped out.

“Ghosn can help them to reverse that loss — he understands how to drive profit margins from cars,�? said Reale. “It’s not that GM can’t do it on its own, but the expertise will help them to do this and get on the path to profitability.�?

The addition of Ghosn to GM’s strategic team would certainly be a benefit to the U.S. firm, but what an alliance would bring to Nissan and Renault is less clear said Reale. In terms of market share, GM has a presence in Europe, although an association with Renault could bring greater exposure. And Nissan has a presence in Japan that GM doesn’t have.