Preheat oven to 325°.
Beat sugar and margarine at medium speed of a mixer until well-blended (about 5 minutes). Gradually add egg substitute, beating well.
Combine sour cream and baking soda. Stir well; set aside. Combine flour and salt. Add flour mixture to creamed mixture alternately with sour cream mixture, beginning and ending with flour mixture. Stir in vanilla.
Pour batter into a 10-inch tube pan coated with cooking spray. Bake at 325° for 1 hour and 35 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 10 minutes; remove from pan. Let cool completely on a wire rack.
Note: Eight egg whites can be used in place of egg substitute, if desired. Add one at a time to sugar mixture.