[Two Bills]

Off airport is usually cheaper, but in all the years wife and I rented we never got much of a discount for our 3-4 months rental.
We had regular updates for offers etc. and saved a lot of $$$ that way.
We used to take up offers and use the free cancel option if a better deal came along. Often with the same company.
Sometimes airlines offered a car rental discount if you flew with them, but that seems a thing of the past now.
Everyone seems to want to squeeze the last $ out if you nowadays.