protected void btn1_Click(object sender, EventArgs e)
    {
        string filename = MapPath("~/App_Data/WanhatAutott.xml");

        grid.DataSource = BLAutot.GetCars(filename);
        grid.DataBind();
    }
    protected void BindGridView()

    {
        string filename = MapPath("~/App_Data/WanhatAutott.xml");

        grid.DataSource = BLAutot.GetCars(filename);
        grid.DataBind();
    }