Ms. Simmons told AdAge.com she didn't want to move back to Detroit for a routine rotation in another Ford Motor Co. position for personal reasons. Ford holds a controlling stake in Mazda.
She said she expects to leave the automaker in a few weeks, and that she already has a position as senior vice president at another marketer not in the automotive industry. She declined to name the company.
No successor was immediately named.
Ms. Simmons spent four of her eight years at Ford with Mazda, with prior marketing stints at Fruit of the Loom and consultancy R.L. Polk. She rose to her current position in April 2001 from marketing director and has overseen Mazda's $175 million budget.
Independent ad agency Doner, Southfield, Mich., handles the automaker's advertising account.