The "9-Euro-Ticket" was a historic, one-time experimental offer in Germany that ran during the summer of 2022 (June, July, and August). During those three months, a staggering 52 million tickets were sold to the public. This massive figure does not even include the roughly 10 million people who already held existing monthly transit subscriptions and were automatically converted to the 9-euro price point. The experiment was designed to provide financial relief during the energy crisis and encourage a shift from cars to public transport. In 2026, while the 9-euro ticket is no longer available, its success led directly to the creation of the permanent Deutschlandticket (D-Ticket), which currently offers unlimited regional travel for a higher monthly price (currently around €58). The 9-euro ticket remains a global case study in "induced demand," as it showed that drastically lowering the price barrier can result in tens of millions of people choosing trains over cars, ultimately saving over 1.8 million tons of CO2 during its short three-month lifespan.