Weirdly it's not the RON number you really need to be interested in but the MON level...
The Research Octane Number (RON) gives a good view on Knock properties at low RPM (slow corner, beginning of re-acceleration). For example, RON is important for Motocross because they are always in re-acceleration.
The Motor Octane Number (MON) gives a good view on Knock properties at high RPM (speed races). The MON is important in competition where speed is the main target.
You should be aware that high octanes are not required for all kind of engines: Turbo and 2 stroke engines need high octanes, but 4 strokes engines with high RPM need a higher speed of combustion than octane.
The second interesting fact I found from a friend that is a chemical engineer is that the cheaper fuels are usually failed or cast off fuels from the bigger companies where is doesn't make their specification to pass certain EN regulations or requirements.
This is then sold to supermarkets where it is (in the same plant) given cheaper additives so that it burns to the EN requirements and passes emissions.
However this cheaper fuel is more prone to absorption of moisture and other air and moisture borne crap that then becomes mixed with the fuels.
Although it burns fine and your engine "go's" is all the rest of the crap being ingested by your engine, fuel system, injectors and sensors that contaminates everything thing around it.
I remember that a number of supermarkets in 2010 has issues with there fuel because it had silicone in it and Asda was taken to court (and ASDA lost) due to dirt in their fuels.
To a degree fuel will still burn and make our cars go, it's whether you keep using cheaper brands and have more costly problems in the future or pay a little more for better quality and also wave your VPower fuel card around when you collect your points xthumbup
