Preheat oven to 375° F. Line a muffin pan with muffin liners and set aside.
In a medium bowl, mix together vegetable oil, eggs, granulated sugar, brown sugar and vanilla until well combined. Set aside.
In a large bowl, whisk together flour, baking soda, baking powder, salt and cinnamon. Add wet ingredients to the dry ingredients and stir until combined (be careful not to over mix). Add shredded zucchini and carrot, and stir until incorporated.
Use a spoon (or an ice cream scoop) to transfer batter into prepared muffin pan until each cup is about three-quarters full. Sprinkle with additional cinnamon sugar if desired². Bake at 375° F for 20 minutes, or until a toothpick inserted in the center of a muffin comes out with little to no crumbs.
Cool muffins in the pan for 3 minutes then remove muffins to a wire cooling rack. Serve warm or at room temperature. Store in an air tight container at room temperature for up to 5 days.
Pat the veggies mostly dry with a paper towel before measuring/weighing.
Cinnamon sugar topping: Stir 2 tablespoons granulated sugar and 1 teaspoon cinnamon in a small bowl and sprinkle over the muffins before baking.
Healthy substitutes: Replace oil with 2/3 cup applesauce (or do 1/3 cup applesauce 1/3 cup vegetable oil). Whole wheat flour may also be used.
Kitchen scale to weigh ingredients (it's more accurate than measuring them)