Ошибки алгоритма

#include <iostream>
#include <string>
#include <cstdlib>
 
using namespace std;
class Vehicle {
public:
    virtual std::string getTypeName() const = 0;
    virtual double getMaxSpeed() const = 0;
    virtual int getWheelsCount() const = 0;
};
 
class Factory {
private:
    class Bus : public Vehicle {
    public:
        std::string getTypeName() const {
            return "Bus";
        }
        double getMaxSpeed() const {
            return 80.0;
        }
        int getWheelsCount() const {
            return 6;
        }
    };
 
    class Truck : public Vehicle {
    public:
        std::string getTypeName() const {
            return "Truck";
        }
        double getMaxSpeed() const {
            return 120.0;
        }
        int getWheelsCount() const {
            return 10;
        }
    };
 
    class Car : public Vehicle {
    public:
        std::string getTypeName() const {
            return "Car";
        }
        double getMaxSpeed() const {
            return 200.0;
        }
        int getWheelsCount() const {
            return 4;
        }
    };
 
public:
    enum VType { VT_BUS, VT_TRUCK, VT_CAR };
 
    Vehicle * getVehicle(VType vtype) const {
        switch (vtype) {
        case VT_BUS:
            return new Bus();
        case VT_TRUCK:
            return new Truck();
        case VT_CAR:
            return new Car();
        default:
            return 0;
        }
    }
};
 
/***************************************************/
 
int main() {
    
 
    Factory factory;
    Vehicle * bus = factory.getVehicle(Factory::VT_BUS);
    Vehicle * truck = factory.getVehicle(Factory::VT_TRUCK);
    Vehicle * car = factory.getVehicle(Factory::VT_CAR);
 
    
 
    delete bus;
    delete truck;
    delete car;
 
    system("pause");
    return 0;
}