cariterator.cs

public class CarIterator : IVehicleIterator
{
    private List<string> _cars;
    private int _current;
    public CarIterator(List<string> cars)
    {
        _cars = cars;
        _current = 0;
    }
    public string Current()
    {
        return _cars.ElementAt(_current);
    }

    public void First()
    {
        _current = 0;
    }

    public bool IsDone()
    {
        return _current >= _cars.Count;
    }

    public string Next()
    {
        return _cars.ElementAt(_current++);
    }
}