I have to agree a very good post from Perusal. I have taken a different approach and do use supermarket fuels , but then dose each tank with Millers Power Ecomax using 1ml per 1 Litre of fuel. 60 buys a 5litre container which is enough for 5000 litres of fuel or quite a lot of miles. Of course this works out a hell of a lot cheaper than buying Vpower and the like. As I tend to keep my vehicles around 10 years or longer I hope to reap the long term benefits.
As I understand it after swallowing some of the marketing Hype, additives like Millers increase the Lubricity of the Derv which in turn helps to preserve the fuel pump system, as well as increase the cetane rating (combustibility) of the base fuel which means a cleaner burn and less smoke to clog a DPF filter. Having used it in quite a few cars I found it did reduce the smokey exhaust on my Euro111 spec Signum 3.0 as well as provide smoother running. A little subjective observation possibly, but perhaps Perusal could comment with more authority?
In truth I have never bought into fuel additives though that's not to say there are not benefits to be had. Millers are a highly regarded company. However a standard fuel provided by any of the majors should suffice since the adpacks used in the fuels should provide all the necessary detergency, combustion improvers and lubricity agents necessary.
The lubricity issues arose with the introduction of ultra low sulphur fuels whereby sulphur is removed from the fuel during the refining process. Sulphur is a very good anti-wear/ extreme pressure agent so while we were busy reducing sulphurous emissions we were also harming anti-wear properties.
I guess the use of an aftermarket adpack such as that described would be useful for a period of time if you are buying a second hand car about whose history you know nothing if only to attempt to clean up the engine.
As I alluded to above, I purchase 95%+ of my fuel from the major brands usually on the basis of price, it has to be said, since I do believe they will all be pretty much on a par although they may have got there using different chemistries. I cannot see the benefits of having just spent nigh on 24K on a new car and then saving about 25 a year on fuel. It's a bit like feeding your kids on supermarket brand burgers, it will do the job but wouldn't you want to give them the best (if you can afford to, that is ), less chance of 'eating horse' as they say.......but each to their own
...and I should perhaps add, that my speciality was in lubricants rather than fuels, though when you sit next to the fuels folk and have lunch with them over 25 years one is bound to pick something up
Believe me, if misunderstandings occur with fuels they are nothing compared to some of the things I have read about engine oils where specification and grade are constantly confused but that's a story for another day!