Preheat oven to 325 degrees.

Grease and flour a 12 cup Bundt pan.

In a large mixing bowl with a mixer, blend the cake mix, sugar, sour cream and oil on low speed for 1 minute.

Add the eggs one at a time, blending well after each addition.

Increase the mixer speed to medium and beat for 4 minutes.

Add the vanilla extract.

Fold the chocolate chips into the batter by hand and stir gently until they are well distributed.

Pour the batter into the prepared pan and bake for 50 minutes, or until a tester inserted in the middle of the cake comes out clean.

Remove the cake from the oven and allow it to cool in the pan.

Invert the cake onto a plate and serve.