C++ dynamic_cast to subclass and trying to access to attribute

I have following Classes:

class Vehicle
{
public:
    Vehicle(int id);
    virtual int getID() const;
    virtual void setCustom(Customer* custom);
    virtual Customer *getCustom() const;
    virtual void printOnce() const = 0;
protected:
    int id_;
    Customer* custom_;
};


Vehicle::Vehicle(int id)
    : id_{id}, custom_{nullptr}
{

}

class Car : public Vehicle
{
public:
    Car(int id, int seats, string color);
    virtual void printOnce() const override;
private:
    int seats_;
    int color_;
};

Car::Car(int id, int seats, string color)
    : Vehicle(id), seats_{seats}, color_{color}
{

}

class Customer
{
public:
    Customer(string customerName, int age, int driverlicenceType);
    string getCustomerName() const;
private:
    string customerName_;
    int age_;
    int driverlicenceType_;
};

Customer::Customer(string customerName, int age, int driverlicenceType)
    : customerName_{customerName}, age_{age}, driverlicenceType_{driverlicenceType}
{

}

string Customer::getCustomerName() const
{
    return customerName_;
}

and the following Method:

Vehicle *CarRental::findByName(string name)
{
    auto cmp =[name](Vehicle* v){
        if(v->getCustom() != nullptr) {
            return name == v->getCustom()->getCustomerName();
        }
    };

    //find Vehicle in vector <Vehicle*> vehicles_;
    return (*find_if(vehicles_.begin(), vehicles_.end(), cmp));
}

Now I'm trying to get the Vehicle*, cast it to Car*, and test if the Customer is nullptr.

Code:

Vehicle* veh = findByName(name);
Car* c = dynamic_cast<Car*>(veh);

    if(c->getCustom() == nullptr) {
        //do anything
    }

But somehow it isn't nullptr. If I try to get the name or age:

cout << "Customer: " << c->getCustom() << endl;

it shows me only Customer: (like an empty string). I think if it were nullptr this should not work and give me an error but I don't know why.