"john2" wrote in message
...

Depends on the engine management software. My old Saab 9-3 LT gives 10%
improved consumption using "big name" brands like Esso or Shell compared
to the bottom of barrel stuff from Tesco, Asda and cut price independents.
So for paying 1-2% more there's a 5-fold return.

That is unlikely.
There is virtually no difference between them and they frequently come from
the same tank.