Having owned two of this model, all I can say is that it hugely depends on the type of driving and the driving style. As long as you accept that this is not a go-cart model, and is intended for comfort without special zest, then I have had up to 44mpg on long sedate trips (2 up with luggage) and down to 27mpg doing the whole - only to shops and local cold run - bit.
Overall I would reckon on 38-40mpg on mixed driving.
Also I have an weird personal theory that the engine control system acts to deter overworking the engine below about 5K miles and only reaches peak performance after around 15K. It may just be the 'running in' happening, but it has occurred on both my 1.4 B-Maxes. This has led to improvement in consumption at these break points.