Similar to the deal I got last year this comes thanks to Mr Pickles - Book a w/e car rental with AVIS and ensure a Friday night pick-up using code 'tuea002' in the box for coupon code for 2 free Reward Weekend Days and you get your rental for free or just taxes. I just tested on the Avis site and it worked. Bring a copy of your booking to the counter just in case. Block book every weekend from now to eternity while the code lasts. - Enjoy!
Note: Some good advice from InACents to have a backup plan just in case.. .