using System;

using System.IO;

using System.Collections.Generic;

using System.Xml.Serialization;

public class Program

{

    public static void Main()

    {

        var serializer = new XmlSerializer(typeof(Carpark));

        using var sr = new StringReader(xml);

        var cp = (Carpark)serializer.Deserialize(sr);

        cp.Dump();

    }

    static string xml = @"

    <Carpark>

   <Trucks>

      <Truck brand='Chrysler' kg='2100'/>

   </Trucks>

   <Cars>

      <Car brand='Mercedes' kg='1100'/>

   </Cars>

   <Tractors>

      <Tractor brand='John Deere' kg='1500'/>

   </Tractors>

</Carpark>";

​

    public class Carpark

    {

        public List<Truck> Trucks { get; set; }

        public List<Car> Cars { get; set; }

        public List<Tractor> Tractors { get; set; }

    }

​

    [XmlInclude(typeof(Truck))]

    [XmlInclude(typeof(Car))]

    [XmlInclude(typeof(Tractor))]

    public class Vehicle

    {

        [XmlIgnore]

        public string Type => this.GetType().Name;

        [XmlAttribute("brand")]

        public string Brand { get; set; }

        [XmlAttribute("kg")]

        public int Weight { get; set; }

    }

    public class Truck : Vehicle

    {

    }

    public class Car : Vehicle

    {

    }

    public class Tractor : Vehicle

    {

    }

}