These two, and several others spotted during a weeklong visit, seem to make their rounds in the greater Miami area much like ice cream trucks in New York. (Come to think of it, I didn't see any ice cream trucks in Miami, though the weather was ideal.) Most announce their appearance with a few honks of the horn or a recorded jingle. "La Cucaracha" was one; mobile vendors are seldom rewarded for subtlety.
Various locations, Miami
(From an autumn 2012 visit)