Beat together sugar, oil and eggs in large bowl or in food processor. Beat in flour, cinnamon, salt, baking soda and powder and vanilla. Beat 1-2 minutes until well mixed. Fold in zucchini, carrot, oats, and nuts; mix well. Pour into 15x10 x1 inch pan (jelly roll pan or cookie sheet with sides). Bake at 350 for 15-20 minutes. Make frosting by beating all ingredients together until smooth. Set aside. Cool bars; frost. Cut into bars. Yield 3 dozen.