Preheat oven to 350°F (175°C). Line a muffin tin with paper liners.
In a large bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
In another bowl, mix the oil, sugar, eggs, and vanilla extract until well combined.
Add the wet ingredients to the dry ingredients and mix until just combined.
Fold in the grated carrots and raisins.
Divide the batter evenly among the muffin cups.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.