Quality Fuel vs Supermarket fuel - what's the real truth?

[The_Laird]

There was a question on this in the motoring pages of the Sunday Times yesterday and the reply was adamant that supermarket fuel was just as good as the premium fuels from Esso and BP, with only Shell giving more mpg. They were also adamant that all the fuel comes from the same depots and only the additives make it different.

BUT... in a conversation recently with the guru of all things motorised (sometimes known to we mortals as Ben) he suggested that supermarket fuel is often close to its sell-by date and nasty stuff is added to make it meet the required standards. And the nasty stuff is bad fior your engine.

So, is the truth with Ben or The Sunday Times - anyone have inside knowlwdge?