public class MotorVehicle extends Vehicle {
    private Engine engine;
    public MotorVehicle(int numberOfWheels, Engine engine) {
    super(numberOfWheels);
    this.engine = engine;
    }
   public String toString() {
      return "MotorVehicle With " + getNumberOfWheels() + " Wheels.  " + engine;
        }
    }