In a mixing bowl, with an electric mixer, beat together sugar, oil, cinnamon, and vanilla.
Add eggs one at a time, beating well after each addition.
Mix in the milk, flour, baking powder, and salt, stirring until just blended. Stir in the apples.
Pour into a greased 9-inch square pan. Bake at 350 degrees Fahrenheit for 30-40 minutes or until the cake springs back when touched in the center.
With a fork pierce cake all over. Pour warm caramel topping all over the cake and then serve warm or at room temperature with a dollop of whipped topping.