Preheat oven to 350°F. Grease an 8x4-inch or 9x5-inch loaf pan with nonstick cooking spray or butter.
Whisk flour, baking powder, baking soda, and salt in a small bowl. Set aside.
Add oil and both sugars to a large bowl. Stir until smooth.
Mix in cinnamon, eggs, and vanilla extract.
Stir in flour mixture, mixture will be thick. Add zucchini and stir until combined – mixture will get looser and more pourable after stirring in zucchini.
Pour batter into prepared pan. Bake 50-60 minutes (9x5-inch pan) or 55-65 minutes (8x4-inch) pan, or until a toothpick comes out clean from the center of the loaf.
Cool before slicing or removing from the pan. Store covered for up to 2 days or freeze for up to 3 months.