In Nov and Dec Universal had many unrented cars when it charged the optimal price

In Nov and Dec, Universal had many unrented cars when it charged the optimal price. That optimal price is based on demand and internal costs. Why might you want to reduce fleet size below the number of cars you could rent at those optimal prices? (Hint: think about why you raised price even when revenues were decreasing when you calculated Nov and Dec optimal prices. How is reducing fleet below what you could rent at the optimal price similar?)