Well the experiment has ended, and on this fill I got 22.2 to the gallon, driving conditions were much the same as before, just in case you were thinking otherwise.
However, what I am about to say I will stand by, as (IMO) it can easily be proven, so I really don't care if you all look at your monitors thinking "Yeah, yeah whatever". I'd say I was a level headed kind of person, very logical and a realist but...
When using this fuel, I did notice an obvious difference in the way the car ran and accelerated as it was evidentially smoother (was that down to the cleaning agents in the fuel). When you bury the accelerator pedal in the carpet the revs climb easier and quieter (engine noise) and getting up to speed seemed less of an effort.
Bonkers? Well before you flame me try it for yourself. Remember though that on the fill before this one (the one that gave me 21.8MPG) my car was fully serviced, and had its No 4 injector replaced, so this 'test' is based on these two fills I've had since and I think a very fair comparison.
And, yes, I went back to BP to refill to me it was a 'no brainer'.