From the Smoking Gun:
Specifically, the 42-year-old actress will not visit the Bronx in service of shilling the subcompact car.
While Lopez, Fiat, the automotive firm’s PR people, and its Detroit ad agency would have consumers believe that the star deigned to return home to film a low-speed pilgrimage through the gritty streets of her hometown, she actually never set foot in the Bronx during the filming of the Fiat spots.
Instead, the role of “Jenny from the Block” was played by a body double, according to two sources familiar with the commercial production. While the Lopez lookalike was actually behind the wheel in the Bronx, Lopez herself was in Los Angeles, where she was filmed inside a Fiat 500.
The shots of the actress were artfully merged to make it appear that she was tooling around New York City’s poorest borough. Big Block, a Los Angeles digital production studio, was hired to merge live action footage with computer-generated imagery to make it appear as if Lopez was in the Bronx.
A new 60-second Fiat spot that debuted last Thursday shows Lopez driving a limited edition Fiat 500 through Manhattan. Like “My World,” Lopez was digitally put into the city.
Here's the Bronx video. Note the urban stereotypes.