public List<Car> FindNewestCars()
{
    List<Car> result = new List<Car>();
    DateTime latestDate = allCars[0].BuiltDate;

    foreach (var car in allCars)
    {
        if (DateTime.Compare(latestDate, car.BuiltDate) > 0)
        {
            latestDate = car.BuiltDate;
        }
    }

    foreach (var car in allCars)
    {
        if (DateTime.Compare(latestDate, car.BuiltDate) == 0)
        {
            result.add(car);
        }
    }

    return result;
}