When must you switch on the hazard lights on your vehicle?

You answered correctly. Hazard lights must be used when your vehicle breaks down in a place where it is difficult for others to see you, helping to warn approaching drivers. They are also required when your vehicle is being towed, so other drivers are aware that your vehicle is not operating as usual. However, hazard lights should not be used just because you are double-parked for a short time; this is not allowed in German traffic regulations. Remember: hazard lights are for alerting others to emergencies or special traffic situations—not for signaling illegal or brief parking.