An Avis "Double Upgrade" is a specific promotional offer or loyalty perk that allows a renter to drive a vehicle that is two car classes higher than the one they actually reserved and paid for. For example, if you book a "Compact" car (Group B), a double upgrade would move you past the "Intermediate" class (Group C) and into a "Standard" or "Full-Size" vehicle (Group D or E). This is a common benefit for high-tier members of loyalty programs, such as the Avis Preferred President's Club or various corporate and credit card partnerships. The upgrade is typically "subject to availability" at the time of pickup; if the higher-class vehicles are not on the lot, the agent may only be able to provide a single upgrade or none at all. It is important to check the terms of the specific "Double Upgrade" coupon or voucher, as there are usually "ceiling" limits; for instance, many vouchers state that the maximum upgrade is to a "Premium" or "Luxury" car (Group G), meaning you cannot use it to jump from a sedan into a high-end SUV or a specialty convertible.