Preheat the oven to 350 degrees F (175 degrees C). Generously spray a 9- or 12-cup fluted tube pan (such as Bundt®) with baking spray.
Cream together sugar, butter, and margarine until light and fluffy, scraping down the bottom and sides as needed, about 2 minutes. Add eggs on medium speed, 1 at a time, until well blended. Mix in sour cream, canned pumpkin, and vanilla on medium to high speed just until well blended.
Whisk flour, cinnamon, baking soda, and salt together in a separate bowl until blended.
Add dry ingredients to the wet ingredients; stir only until just combined. Scrape down the sides and bottom and finish blending everything together by hand with a spatula. Scrape cake batter into the prepared pan and smooth gently with a spatula.
Bake in the preheated oven until a skewer inserted into the center of the cake comes out clean, 50 to 55 minutes.
Remove from the oven and allow cake to rest for about 15 minutes before carefully inverting onto a cooling rack. Allow to finish cooling before slicing and serving.