The 30-second commercial, set to air during Monday Night Football, features Lopez driving a Fiat 500 Cabrio convertible. At the end, two muscular men pull her out through the open top and she dances in the street.
The Cabrio also appears in the video for Lopez's new single, "Papi."
Olivier Francois, marketing chief for Fiat and Chrysler, says Lopez is passionate and determined to stand out. He didn't say how much Fiat is paying her. It's a second high-profile ad for the Fiat-Chrysler alliance, which featured rapper Eminem in an acclaimed Super Bowl ad.
The Cabrio went on sale in the U.S. earlier this summer. Sales have been sluggish, partly due to delays in opening dealerships.