Hi and welcome.
I have done a supermarket vs premium comparison, but it's Morrison's vs BP/Esso. Both the Premium petrols gave about 10% better mileage in my B-Max (as below), but obviously cost more. Round here the difference in price is about 10% so in terms of cost/mile it seems to work out about the same, but gives more miles in the tank and potential benefits in engine condition if you are keeping forthe long haul.
It would certainly be worth running on each for about a month and see how it goes, but beware the first 2000 miles, asit appears that consumption improves on most of the engines about then! Perhaps Ford have programmed the ECU to change the running conditions after what we old un's used to call 'running in', which they say is not needed nowadays
!
Hopes this helps
Geri
