UPDATE:
According to Hollywood Life, Malo Cantina had some very handsome valet drivers on-duty that evening, and the man in the black car was not Stewart's former fling. One source put it pretty bluntly for the site: "Not a chance in hell [was] she was with Rupert yesterday or anytime recently." There you have it, false alarm. And, for the record, we also learned that her drink of choice is a Cucumber Margarita, not the Piñata Smash.

Photo: Via Crushable