Preheat oven to 180 degrees C. Grease a 23x33 cm pan.
In a large bowl, mix together the eggs, oil, sugar and vanilla until well blended. Combine the flour, baking powder, bicarb soda and salt in a separate bowl; stir into the sugar mixture. Mix in the zucchini. Spread the batter evenly into the prepared pan.
Bake for 20 to 25 minutes in the preheated oven, until a toothpick inserted into the centre comes out clean. Allow cake to cool completely before icing.
To make the icing, blend together the margarine, cream cheese and icing sugar until well blended. Spread over cooled cake before cutting into slices.