Well, I can't speak for the UK or other areas of the world, but in the
all gasoline is of undefinable origins. That is, the oil companies
pump gas into a shared storage pool and draw from it in equal
proportions to what they put in. The only difference in gas at the
pump is the additive package they add and how often and how
effectively they keep the water out of their tanks at the station.

Still, people here claim religiously that their cars run better on
certain brands of gas. I have my doubts since the only real difference
is the octane rating and the detergents they use. As long as the
octane rating is honest, that's out of the picture too. So, we're down
to a difference in detergents - and if your injectors are clean, that
likely does not matter either.

So, I've got my doubts :-)