In a large bowl, sift the sugar and flour together.
In a saucepan on the stove, whisk the butter, vegetable oil, cocoa and Coca-Cola® together. Bring to a boil and pour over dry ingredients blending together well.
Dissolve the baking soda in the buttermilk and immediately add to the batter along with the two eggs, and the extract. Mix together well.
Pour the cake batter into cupcake liners in two muffin pans and bake for 20-25 minutes. Remove when a toothpick came out clean. Remove from oven and allow to cool on wire rack.
For the Frosting
Combine the butter, cocoa and Coca-Cola® in a saucepan over medium heat. Bring to a boil. Remove from heat. Allow to cool.
Once cooled, sift the powdered sugar into the boiling cola/butter mixture, blending together well. Add the vanilla extract. Whisk until fluffy or desired consistency. Easiest with an electric mixer.
Spread or pipe the frosting over each cupcake. Allow to cool. Serve.