In a large bowl, beat together the sugar, oil, pumpkin or squash, and eggs.
In a medium bowl, stir together the flour, baking powder, baking soda, and cinnamon. Fold this into the other mixture just enough to moisten the dry ingredients. If using, stir in the raisins and/or nuts. Pour the batter into a greased 9x5-inch loaf pan.
Bake for 40-50 minutes or until a toothpick inserted in the center comes out clean.