Thanks for that clarification Nick.
I am with you on this - a better informed person could not be found. No disrespect meant to the tanker driver - garfie.
I feel that there are a load of honest, genuine people around, who disbelieve others because they cannot themselves see what it is the others see or find. (Oh dear, I sound like a psychiatrist)
I have done as accurate tests as any member of the public could, I think.
Journeys the entire length of the UK on one brand of fuel, and on to the other side of Europe staying with the same major brand.
400 -500 miles per day for 4 days straight, is enough for me to compare Esso with Shell and BP etc.
The high-tech fuels definitely give better results - both power and mpg, (but perhaps not both at the same time) while the supermarket fuels give poorer results and a smoky exhaust.
No more comparisons are needed for me anyway.
As for Waitrose - which we don't have in Scotlandshire - do they really display BP signs at their supermarkets? Surely if they do then it must be correct, or BP would be objecting, and I expect it could be easily tested.
I would buy from Sainsbury, if it was displayed as BP Ultimate Diesel. That would be a genuine saving.
Regards, Singvogel.