Yes, you can book a car rental online with your AAA discount. AAA recommends booking a car rental as much in advance as possible for best pricing and availability.
AAA’s car rental partners - Hertz®, Dollar®, and Thrifty® - offer AAA member discounts plus special benefits such as waived additional driver fees and free child safety seat. AAA Members and non-members alike should sign up for Hertz Gold Plus Rewards; this free program allows renters to skip the line and save time, choose from a better selection of cars, and earn loyalty points toward free rentals.