We're fans of National's Emerald Club, one of the rental car programs where -- at participating major airports -- members can skip the counter, walk to an aisle of cars, select their preferred vehicle among the available selection, and leave. The Emerald Club offering even allows customers to earn free days and is strengthened even further by the perennial One Two Free Promotion, which allows customers to earn bonus free days. Every member of our team is a member of National's Emerald Club program and we do a little internal "happy dance" when National happens to be the cheapest option for our personal rentals. And yet there are indeed tiers to the Emerald Club that unlock additional benefits. Those "Executive" tiers can be unlocked by at least 12 rentals (or 40 rentals days) each calendar year, as a benefit of certain premium credit cards, or via a status match for those renters who have top-tier statuses in other travel programs.