Preheat oven to 350 degrees F. Grease and flour two 8-inch cake pans. Set aside.
In a medium mixing bowl, stir together the flour, cocoa powder, baking soda, baking powder, and salt until evenly combined. Set aside.
In a large mixing bowl, beat together vegetable oil, butter, and brown sugar until smooth, about 1 to 2 minutes. Add the eggs and vanilla, and beat until smooth. Scrape the sides of the bowl as needed.
Add half of the dry ingredients to the brown sugar mixture. Mix until just combined. Pour in all of the buttermilk and mix until evenly combined. Add the remaining dry ingredients and mix until combined. Scrape the sides of the bowl as needed. Add in the coffee and mix until smooth.
Pour half of the batter into each of the prepared pans.
Bake for 30 to 35 minutes, or until a toothpick inserted in the center comes out clean. Remove cakes from oven and place on wire racks to cool completely.