Simple Dependency Injection

DependencyInjection.cs

namespace DependencyInjection
{
    public interface IMotor { }
    public class Motor : IMotor { }

    public class Auto
    {
        private IMotor motor;
        public Auto(IMotor motor)
        {
            this.motor = motor;
        }
    }

    public static class Factory
    {
        public static Auto CreateAuto()
        {
            return new Auto(new Motor());
        }
    }
}

WithoutDependencyInjection.cs

namespace WithoutDependencyInjection
{
    public interface IMotor { }
    public class Motor : IMotor { }

    public class Auto
    {
        private IMotor motor;
        public Auto()
        {
            this.motor = new Motor();
        }
    }
}