public interface ICar
{
    string Start();
    string Stop();
}

public abstract class Car : ICar
{

    public Car(string model, string color)
    {
        this.Model = model;
        this.Color = color;
    }

    public string Model { get; private set; }
    public string Color { get; private set; }

    public virtual string Start()
    {
        return "Engine start";
    }

    public virtual string Stop()
    {
        return "Breaaak!";
    }

    public override string ToString()
    {
        return $"{this.Color} {this.GetType().Name} {this.Model}";
    }
}

public abstract class ElectricCar : Car
{
    public ElectricCar(string model, string color, int batteries)
        :base(model, color)
    {
        this.Battery = batteries;
    }
    public int Battery { get; private set; }
}

using System;
using System.Text;

public class Seat : Car
{
    public Seat(string model, string color)
        : base(model, color)
    {
    }

    public override string ToString()
    {
        var sb = new StringBuilder(base.ToString() + Environment.NewLine);
        sb.AppendLine(Start());
        sb.AppendLine(Stop());
        return sb.ToString();
    }
}

using System.Text;

public class Tesla : ElectricCar
{
    public Tesla(string model, string color, int batteries)
        :base(model, color, batteries)
    {
    }

    public override string ToString()
    {
        var sb = new StringBuilder();
        sb.AppendLine($"{base.ToString()} with {this.Battery} Batteries");
        sb.AppendLine(Start());
        sb.AppendLine(Stop());
        return sb.ToString().TrimEnd();
    }
}

using System;

public class StartUp
{
    public static void Main()
    {

        Car seat = new Seat("Leon", "Grey");
        Car tesla = new Tesla("Model 3", "Red", 2);

        Console.WriteLine(seat);
        Console.WriteLine(tesla);

    }
}