Preheat oven to 350 F.
In a large bowl beat oil, sugar, eggs, and pumpkin until well combined.
Stir in cinnamon, baking powder, baking soda, and salt. Add flour a little at a time until just combined.
Pour into an un-greased 9x13 baking pan.
Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean.
<b> For the Cream Cheese Frosting </b>
Beat cheese cheese, butter, and vanilla until well combined.
Add powdered sugar a little at a time until just combined.
Spread frosting over cake, and refrigerate until ready to enjoy.