I have a 2013 sky active diesel 6. Normal driving it does 44mpg average, granny it on the mortoway at 60mph and concentrate on economy else where its best to date has been 58mpg from a tank and that was hard work (all calculated not indicated).
Id be amazed if the petrol manages more than 40 combined unless you really drive for economy.
That said 56k and its been faultless so far…
Edit…Just looked, after 65 tanks of fuel the long term mpg is 43.2 - 70% mortorway driving.