Preheat the oven to 350 degrees Fahrenheit.
Grease a bundt pan.
Combine 12 ounces of Mountain Dew, cake mix, vegetable oil, and eggs. Use a mixer and combine thoroughly. Start at a low speed and mix for 30 seconds, then increase speed to medium and mix for another two minutes.
Pour batter into greased pan and place in the oven. Bake for 45 minutes. The finished cake should pass the toothpick test (poke a toothpick into the middle and it should come out clean.
Remove the cake from the pan and let it cool on wire rack.
Once the cake is cool, you can apply the glaze. To make glaze, mix the 1/2 cup of Mountain Dew with powdered sugar. Combine well and ensure there are no remaining lumps. You may want to place some wax paper underneath the wire rack to catch any extra glaze as it falls off the cake.