Avis Preferred is the entry-level tier of the Avis loyalty program, and while it provides significant benefits like "Skip the Line" service and points toward free rentals, it does not guarantee free upgrades. To receive complimentary upgrades, members usually need to reach the higher "Avis Preferred Plus" or "Avis President’s Club" tiers. Avis Preferred Plus members are eligible for a one-class upgrade upon availability, while President's Club members (the top tier) receive a guaranteed one-class upgrade and a double upgrade on weekends when available. That said, entry-level Preferred members may occasionally receive an "operational upgrade" if the car class they booked is sold out, but this is a matter of luck rather than a stated benefit. For the best chance at an upgrade as a basic Preferred member, it is often helpful to book during off-peak times or use specific "Preferred-only" promotional codes found in the Avis mobile app or monthly email offers.