In a large bowl combine flour, sugar, baking powder, and 1/4 teaspoon salt; make a well in center. Add oil, egg yolks, vanilla, and 3/4 cup cold water. Beat with an electric mixer on low speed until combined. Beat on high speed about 5 minutes or until satin smooth. Fold in orange and lemon peels; set aside.Thoroughly wash beaters. In a very large mixing bowl beat egg whites and cream of tartar on medium to high speed until stiff peaks form (tips stand straight). Then pour beaten mixture in a thin stream over egg yolk mixture and gently fold in. Gently pour batter into an ungreased 10 inch tube pan. Bake in a 375F oven for 65 to 70 minutes or until top springs when lightly touched. Remove from oven. Immediately invert cake in pan and cool completely. Using a narrow metal spatula loosen the sides of the cake from the pan. Then remove the cake from the pan.