
I've noticed that different petrol (similiar grade) caused the fuel guage to have different fuel consumption pattern. For example,
1) Shell 95; fuel level dropped fastest between 1/2 and 1/4 mark. Earlier from Full to 1/2 mark the drop is rather slowly.
2) Mobil 95; fuel level dropped fastest between 3/4 and 1/2 mark. Later the drop will be more gradual and evenly.
3) SPC 95; the level drop fastest around 1/2 mark, the rest rather constantly.
4) Caltex...have not tried it yet.
Although I've experienced different fuel consumption pattern as witness from the fuel guage, but overall fuel consumption among the various brand is almost the same, minimal difference. Meaning; a full tank of Shell, or Mobil or SPC will given me around the same mileage travelled until the fuel guage empty light comes on.
This difference in fuel consumption pattern (as observed from fuel guage) is repeatable, meaning its not a one time observation, whenever I use that particular brand the pattern appear again. Also travelling distance, timing and route is same, but its just that different petrol brand caused the fuel guage to give different reading (or different consumption rate?). Its not about the fuel tank profile/shape either, otherwise different brand will still give the same FC pattern, right?
I've check with one of my colleague, and he had observed the same findings...

So, just curious, have you noticed any difference in your fuel guage consumption reading when using different brand?