The last big post on this had a guy in the industry commenting. IIRC the summary was that youll get slight more mpg and performance if your car is able to adjust to the octane rating, and the cleaning content was superior. As above it eas advised to use it once every 4-5 tanks using non supermarket fuel (less additives) in between. Its then your decision whether thats worth paying for.

Over the last 3 years I have been using an app to record the fuel usage of my T5. My local choice of branded fuel is Esso or Shell, so that is what I have mostly used, either the normal or premium diesel. The clear consistent winner in the best mpg stakes is Esso Supreme.

It is hard to separate the normal Esso, Shell and Shell V-power. If anything the Shell V-power is the lowest mpg, and it’s the most expensive. So I tend to use mainly Esso a mix it up a bit between normal and supreme. The increase in mpg of the supreme is alone not quite enough to justify the extra cost.

Not used much BP so can’t say how that compares. Have had good mpg with a few tanks of Texaco, but not enough to get any statistically reliable results.

I generally run from brimmed to around 1/8-1/4 tank before filling, or will fill before a big trip so the tank will last the trip without refueling. Each fill probably covers around 400 miles of mixed driving. Usage is a mix of motorways, A roads, running round country roads, little town driving.

I’ve not noticed any appreciable difference in performance between the fuels, but then my van has plenty of performance so isn’t lacking in go which ever fuel is used.

Edit: When we race the TVR V8 engined Land Rover it definitely pulls better on V-Power. No idea on mpg, when you’re way down in single figures it’s best not to look that closely.