The duties of Mr. Jackson, who oversaw more than $2.3 billion in marketing spending, will be assumed by his boss, Mark LaNeve, VP-sales, service and marketing, North America.
Joined automaker in 2000
Mr. Jackson joined GM in February 2000 as exec director-sales and marketing support, and was posted at GM's headquarters in Detroit; he later moved to California in February 2002 to head up the automaker's western region.
His family still lives in California and he had been commuting to Detroit since becoming marketing chief, the spokeswoman said.
Mr. Jackson initiated dramatic changes during his short tenure as marketing czar, dropping longtime Cadillac agency Leo Burnett, Troy, Mich., and Saturn's agency, Goodby, Silverstein & Partners, San Francisco, without reviews.
Clashes with LaNeve?
There have been reports Mr. Jackson didn't see eye to eye with his boss. But the spokeswoman said Mr. LaNeve and his marketing lieutenant "had a lot of respect for each other."
"Throughout his tenure Mike has contributed to GM's improved product image, and brought a creative approach to GM's market presence," Mr. LaNeve said in a statement. "We wish him well in his future endeavors."