That is high. But fuel economy depends on use. If the car has been used only for short runs from cold then poor economy is to be expected in colder weather. But it should not have been as bad as that through the summer when ambient temperature keeps the engine block above 20 degrees centigrade most of the time. One option is to change fuel, preferably to Shell V-Power petrol and see what effect that has. Another is to have the warm up cycle of the engine diagnostically checked, which would mean leaving the car overnight at a garage to get completely cold before they could check the warm-up cycle.