Longtime Audi veteran Johan de Nysschen, who rose to become president of the company\'s U.S. unit, has resigned for another job that is unknown at this point. COO Mark Del Rosso will handle daily operations until a replacement is named. The moves take effect immediately, Audi spokesman Brad Stertz said. “He\'s announced he\'s resigning for another job,” Stertz told Autoweek. The news came after Audi announced a 10 percent sales increase in May, with 11,503 units sold. It was the best May on record for Audi in the United States and its fifth-best month ever in the market. The news came as a bit of a surprise on Friday afternoon—de Nysschen is still quoted in the company\'s May sales press statement. The 52-year-old has been Audi\'s U.S. boss since December 2004. He also held top posts for the German brand in Japan and his native South Africa. De Nysschen has overseen considerable growth for the brand in both image awareness—the company has become a player in Super Bowl commercials—and sales. Audi\'s share of the luxury market increased from 5.3 percent to 9.5 percent last year, the company said. In an e-mail to Audi workers, de Nysschen explained his move: \"Life\'s journey is full of twists and turns, and sometimes these bring one to an unexpected juncture. And so it is for me in this instance. I\'m a car guy. And Audi has been \"my car\" since 1973. I have never even imagined my world without Audi being right at the center. But, this is the real world, and I guess sometimes unforeseen things just happen. \"I do want to make it very clear--this development is unrelated to the present discussion and expectations of reorganization of senior roles inside the VW Group. Rather, it comes from a realization of the future leadership needs of Audi, in order to attain our goal of becoming the most aspirational premium brand in the U.S.\" He then elaborated: \"I\'d like to think you know me. The spirit of Audi roars within my heart. However, after much reflection, I have the very clear conviction that Audi is at a new inflection point in the ongoing development of the brand in the U.S.--and this demands leadership with new insights and a philosophy which is more appropriate for this new phase for the company. I dearly love this company and all it represents. I thrive on developing turnaround strategies and on building companies, but Audi of America is no longer a construction site. It needs leadership with a different skill set. I want Audi to win. But I too, need to secure my future, and must play to my own strengths. Stepping aside for new leadership, and setting forth to seek out a new \"construction site,\" in a manner of speaking, is a painful but appropriate decision at this time. A win-win, if you like. Such an opportunity presents itself at this time, and I have decided to accept this new challenge.\" De Nysschen also was at the helm when Audi moved its U.S. headquarters from suburban Detroit to Virginia. Del Rosso, 48, has been with Audi for more than four years after a long stint with Toyota Motor Sales USA Inc.