Mr. Winterkorn, with a reputation for delving deeply into the minutiae of automobile design and construction, became chief executive in 2007, two years before the deceptive software was evidently introduced with the 2009 model year. He continues to retain control over research and development.
Volkswagen declined to say where the 11 million affected vehicles — more cars than Volkswagen produces in a year — were. But analysts said that as many as 10 million were probably in Europe, where Volkswagen is the dominant manufacturer, with more than double the market share of any competitor, and where diesels account for more than half of all vehicles sold.