Bug in valueOf #29

package symjava.test;
public class TestValueOf {
    public static class Car {
        public int id;
        public Car(int id) {
            this.id = id;
        }
        public Car add(Car c) {
            return new Car(this.id+c.id);
        }
    }
    public static class Jeep extends Car {
        public Jeep(int id) {
            super(id);
        }
        public static Jeep valueOf(Car c) {
            return new Jeep(c.id);
        }
    }
    public static void main(String[] args) {
        Car c1 = new Car(1);
        Car c2 = new Car(10);
        Car c12 = c1 + c2;
        //Jeep j = c12; //works
        //Jeep j = Jeep.valueOf(c1 + c2); //works
        Jeep j = c1 + c2; //NOT work!!!
        System.out.println(j.id);
    }
}