Jenny returned to the block ... in a Fiat.

Jennifer Lopez is keeping us on her toes as the new Fiat spokeswoman, this time driving a 2012 Fiat 500 through her old Bronx neighborhood.

"This place inspires me to be tougher, to stay sharper, to think faster," she says in the "My World" commercial. "They may be just streets to you but to me they're a playground."

We'll give her this -- she looks extremely happy to let her hair down (literally) and hug all the kids she comes across on the street.