Preheat oven to 325°F. Grease an 8 ½-inch x 4 ½-inch loaf pan with butter or nonstick spray. In a small bowl, stir together the cinnamon-sugar mixture.
Sprinkle about 3 tablespoons of the cinnamon-sugar mixture around the bottom and sides of the greased pan. Set aside.
In a large bowl, mix together the zucchini, oil, eggs, and vanilla extract. Whisk the sugar into the zucchini mixture until the sugar completely dissolves and the mixture is creamed together.
In a separate bowl, sift or whisk together the flour, salt, cinnamon, baking soda, and baking powder.
Add the sifted dry ingredients to the wet ingredients. Stir just until combined. The batter should be smooth, with the exception of the shredded zucchini. Be careful not to over-mix the batter.
Pour half of the batter into the prepared pan. Sprinkle half of the remaining cinnamon-sugar mixture over the batter. Add the rest of the batter to the pan; sprinkle the remaining cinnamon-sugar on top.
Bake for approximately 55 minutes, or until the bread springs back when gently pressed in the middle and a toothpick inserted in the center comes out clean. Allow to cool for 15 minutes before removing from the loaf pan. Slice and serve warm, or cool completely on a wire rack.