Note that at participating Avis/Budget locations in the U.S., the AARP rates includes a small amount of
primary third-party liability insurance, and also limits your liability for rental-car loss or damage to just $5,000 (assuming that you do not pay for Avis' expensive LDW coverage). Your personal auto-insurance policy and the credit card you use for the rental may also provide some coverage
Details of the special Avis/AARP coverage here:
https://www.avis.com/en/association/A359807
(Scroll down to "Additional Benefits.")
Be sure to have your current AARP membership card with you; some Avis/Budget locations ask for it when a renter has booked the AARP rate.