How many rentals in a year do you think would make it worthwhile to purchase this?
Hard to say as there are a lot of intangibles.
The bennies are:
-5 free days in a luxury car upon signup.
-The station manager meets you when you get off the shuttle bus and pulls up the best car on the lot to the front so you can be out within 60 seconds. Alternatively you can call ahead and have them bring the car to the terminal, but not all locations can do this.
-Rent a midsize and get your pick of cars. Usually I get a CTS or G37.
-Pay market rates on gas so you don't need to fillup before returning.
-They will deliver and pickup a car anywhere within 25 miles of an Avis location for free.
-They will chauffeur you back to the terminal in your car so you don't have to shlep your bags and wait for the shuttle bus.
-Guaranteed car even if the location is sold out.
Basically though you are treated like royalty when you rent. They don't look over the car when you return it or make you crazy about anything.