Andy1GP, yes, the data does include the one fill-up where all indications are that I paid for 20 litres more than was pumped. (Apart from my consumption data clearly showing this, it was quite a bit more than the tank holds when empty, which it wasn't - the fuel light wasn't even lit.) It does, however, not have much of an effect on the results, because of the amount of data.
In fact, the way I presented the data actually makes the Sasol numbers appear better than they are, since I have only averaged the individual fuel consumption figures at each fill-up. If you calculate the overall consumption using total litres and total mileage driven, you will see that the Sasol data looks quite a bit worse (8.63 instead of 8.36 l/100km). The calculated consumption of the "bogus" fill-up was around 11.8 l/100km, which is WAY more than I have ever seen before, or since, and clearly incorrect. The OBC value at the time was also no higher than normal.
The fact that my protestations to this effect are largely being ignored leads me largely to ignore Sasol garages in future! Why should I go out of my way to try another branch of a franchise where one example has, based on my data, either: 1. Overcharged me on a number of occasions, or 2. Is supplying fuel which is less efficient and/or more variable than the other option I have tried? Also, there isn't another Sasol garage conveniently located on my daily commute.
I had also believed the Sasol diesel to be better (also based on heresay), which is why I was using it. When I believe I've been short-changed I vote with my feet, however, and am only reporting what I've seen since.
