General Motors’ car assembly plant in Van...

General Motors’ car assembly plant in Van Nuys might be one of five plants closed by the nation’s major auto makers over the next five years, according to a study by J. D. Power & Associates, an auto research firm in Agoura Hills. J. D. Power analyst Chris Cedergren said, “This doesn’t necessarily mean these plants will be closed.” But, he said, they’re currently candidates for closure because their efficiency and the quality of their vehicles are lower than those of other plants.