In which situations should you switch off the engine to save fuel and reduce environmental pollution?

Your answer is correct because according to German traffic rules, you should switch off the engine to save fuel and reduce pollution when you expect to wait for a longer period, such as in a traffic jam or at a gated level crossing. This is because idling uses fuel unnecessarily and increases emissions. However, stopping briefly at a "Stop" sign does not usually require turning off the engine, as the wait is typically short and frequent restarting can cause more wear and emissions. Understanding this helps you reduce fuel consumption and environmental impact in situations with extended stops.