Question : Contravariance in Predicate delegates in C#

In .net 4.0, this code will run correctly, but in 3.5 it will not. If I uncomment the individual ByID methods, the code works correctly. Is there a better way, or is that the best solution?

class Vehicle
    {
        public int ID {get; set;}
        public Vehicle()
        { }
        public Vehicle(int id)
        {
            this.ID = id;
        }

        public static Predicate<Vehicle> ByID(int id)
        {
            return delegate(Vehicle vehicle)
            {
                return vehicle.ID == id;
            };
        }

    }

    class Auto : Vehicle
    {
        public Auto(int id)
        {
            this.ID = id;
        }

        //public new static Predicate<Auto> ByID(int id)
        //{
        //    return delegate(Auto auto)
        //    {
        //        return auto.ID == id;
        //    };
        //}

    }

    class Plane : Vehicle
    {
         public Plane(int id)
        {
            this.ID = id;
        }

         //public new static Predicate<Plane> ByID(int id)
         //{
         //    return delegate(Plane plane)
         //    {
         //        return plane.ID == id;
         //    };
         //}

    }

Attachments:

Class1.cs (1 KB) (File Type Details) 

Class file

Program.cs (824 bytes) (File Type Details) 

Console App

Answer : Contravariance in Predicate delegates in C#

http://stackoverflow.com/questions/1089196/selectsinglenode-returning-null-for-known-good-xml-node-path-using-xpath

http://www.devguru.com/technologies/xmldom/quickref/node_selectsinglenode.html