In small bowl, blend sugar, cinnamon, and cream of tartar. Set aside.
Bread:
In large bowl, thoroughly mix wet ingredients: oil, eggs, sugar, and vanilla.
In medium bowl, thoroughly mix dry ingredients: flour, cinnamon, baking soda, salt, and cream of tartar.
Stir dry ingredients into wet ingredients until everything is wet, no dry spots. Do not over-mix.
Fold in grated zucchini.
Heavily spray non-stick spray in 2 - 8 1/2" x 4 1/2" loaf pans.
Fill each pan 1/3 full of batter.
Sprinkle 2 tablespoons of topping over each loaf.
Evenly divide remaining batter between 2 pans. Sprinkle remaining topping over tops of both loaves.
Bake for 45 - 55 minutes. Check for doneness: insert toothpick or knife in center of bread. It should come out clean. If it still has mushy batter, bake another 5 minutes, and re-check.
Remove from oven and allow to cool on wire rack. Enjoy!