using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp3
{
    class Program
    {
        static List<CarModel> model = new List<CarModel>()
        {
            new CarModel{CarModelName="E30",CarModelID=1},
            new CarModel{CarModelName="M5",CarModelID=1},
            new CarModel{CarModelName="E220",CarModelID=2},
            new CarModel{CarModelName="E230",CarModelID=2},
            new CarModel{CarModelName="RS8",CarModelID=3},
            new CarModel{CarModelName="RS7",CarModelID=3},
        };

        static List<Car> car = new List<Car>()
        {
            new Car{CarName="BMW",CarID=1},
            new Car{CarName="Mercedess",CarID=2},
            new Car {CarName="Audi",CarID=3}
        };

        static void Main(string[] args)
        {
            var result = car.GroupJoin(model,
                i => i.CarID,
                p => p.CarModelID,
                (car, model) => new
                {
                    Name = car.CarName,
                    Model = model.Select(p => p.CarModelName)
                }
                );

            foreach (var item in result)
            {
                Console.WriteLine(item.Name);

                foreach (var s in item.Model)
                {
                    Console.WriteLine(s);
                }
                Console.WriteLine();
            }
            Console.ReadLine();
        }
    }
}