Preheat oven to 350°.
In a large mixing bowl, cream the margarine, oil and sugar. Still beating, incorporate the eggs, vanilla, milk and all the dry ingredients.
When all the above is mixed well, stir in the grated zucchini and about a cup of chocolate chips, reserving some of the chocolate chips for topping.
Pour into a greased and floured pan – a 9"x13" rectangular pan to a loaf pan, so the end result can be cut in squares instead of slices.
Sprinkle reserved chocolate chips over the top of the batter, and bake for about 40 minutes, or until the edges start to burn a little and a knife comes out clean from the center.