[ace32229]

These things are not true in the UK - all fuel is held to the same high standard, though premium variants are available too.

[gib444]

So no petrol is permitted to be higher quality (for the same octane rating)?

ie you're asserting there is zero variance in quality?

OP wrote lower quality, not low quality

[alexfoo]

By "lower quality" I did mean "low quality".

It's the reverse of "this one is more expensive therefore it must be better" without any evidence at all that it is the case.

[gib444]

Yeah fair enough that's probably true

Companies are permitted to add additives etc but whether that meaningfully improves quality I'm not sure