Preheat oven to 350 degrees. Grease and flour a 9 x 33 cm baking pan. In large mixing bowl, combine flour and sugar; set aside. In small, heavy saucepan, bring margarine, cola and cocoa to boil; pour ovr flour and sugar and mix thoroughly. Add buttermilk, eggs, baking soda, vanilla and miniature marshmallows. Pour into prepared pan and bak 35 minutes or until toothpick inserted into center comes out clean. While cake bakes, prepare Coca-Cola Frosting (you will be frosting the cake while it is still hot). Assorted recipes from the Detroit News, entered by Diane Pahl