As the 90-day alliance discussions between Renault SA, Nissan Motor Co. Ltd. and General Motors Corp. reach their midway point, top executives say they are making progress.

However, Renault and Nissan CEO Carlos Ghosn tells reporters it still is too early to draw any conclusions.

“Things are going well so far,” he says. “There is a good atmosphere.

“We will have a review on where things stand in September and reach a conclusion on the matter by mid-October," Ghosn updates reporters on the sidelines of a businesses conference near Paris organized by French employers’ group MEDEF.

Ghosn declines to confirm reports Ford Motor Co. contacted Renault to open discussions in the event talks with GM fall through.

For his part, GM Chairman and CEO Rick Wagoner tells reporters various teams are meeting according to “an expected schedule.”

“We get reasonably regular updates, certainly not daily, but periodically,” Wagoner says at a Detroit-area event in mid-August. “But this is still fairly early into the process. Frankly some of the work has been each group developing their own data and sitting down and sharing it.”

The three auto makers are examining the cost benefits of sharing facilities, parts procurement, global market territories and vehicle platforms. Wagoner doesn’t say how deeply the auto makers may be sharing future product plans.

Nissan and Renault also are evaluating a potential $3 billion bid to buy a combined 20% stake in GM at the urging of billionaire investor Kirk Kerkorian, who first proposed the tie-up June 30.