The combined fuel consumption quoted on the label on your windscreen is not a real-life figure, it’s the result of a laboratory test, and the aim of it its to provide the buyer with a figure they can use to compare one car with another. The bottom line is that it doesn’t necessarily affect the consumption you might get in real life driving. But I would expect the real life fuel consumption to be closer to the claimed figure than yours appears to be. There are many factors that can affect fuel consumption, ranging from tyre pressures, extra load in the boot, roof racks, driving style etc. I would ask the dealer to demonstrate to you that the car’s fuel consumption is normal, as they claim it is.