A method and system for informing fuel efficient driving are provided. The method includes collecting, by a controller, vehicle context data that includes fuel consumption per second and calculating a fuel efficiency influencing factor that includes a driving time after starting an engine based on the vehicle context data. The fuel efficiency influencing factor is stored in a database and a driving propensity of a driver is analyzed based on the data stored in the database. Further, fuel efficiency analysis data that includes a fuel efficient driving index is produced a fuel efficiency analysis result based on the fuel efficiency analysis data is displayed.