De Nysschen, 58, became president of Cadillac in August 2014 after stints as CEO of Nissan Motor Co.'s Infiniti brand and head of Audi's U.S. business.He was given unprecedented freedom over managing Cadillac, including moving the venerable luxury brand's headquarters out of Detroit to New York City and operating separately from GM's core brands. De Nysschen's abrupt departure comes less than four months after Uwe Ellinghaus, Cadillac's chief marketing officer, left the brand for "personal reasons."