A boy plays with a motorized car next to a dirty street lined with real cars.
a boy played in the streets with his motorized car.
"A boy plays with a motorized car next to a dirty street" is a rephrase of "a boy played in the streets with his motorized car."
in the streets implies that he is around streets, which is a rephrasing of next to a street.
"streets with his motorized car" is a rephrasing of "motorized car next to a dirty street."