class Car
{
    string _plate = "";

    public string Plate
    {
        get { return _plate; }
        set { _plate = value; }
    }

}
class Ferrari : Car
{
    string specialName = "";

    public string SpecialName
    {
        get { return specialName; }
        set { specialName = value; }
    }

    Ferrari (Car obj )
    {
        specialName = (obj is Ferrari) ? ((Ferrari)obj).SpecialName : "";
    }
}

static void ManageCars (Car A)
{
    if (A is Ferrari)
    {
        Ferrari B= (Ferrari) A;
        Console.Writeline("This is a Ferrari! specialName is " + B.SpecialName);
    }
    //else if(A is Mercedes)
    //{
            ...
    //}
    else
    {
        Console.Writeline("This is simple car");
    }
}