Theres been debate on other forums and in my opinion the bottom line is that using super instead of standard 95RON unleaded makes little difference. Some supers claim to help clean an engine and improve fuel consumption but performance-wise, theres not much (if any) evidence to prove an increase. (Only a possible placebo effect.)
I just use 'normal' unleaded and find it works just the same as when I've used super unleaded.
Also most supermarkets get their petrol from the likes of BP and Esso etc so don't be put off, -their sometimes cheaper because they can use the big profits from food sales etc to have cheaper fuel. (& thus entise you in to do some shopping.)
Hope this helps.
A higher octane petrol in a sports engine should technically be better for engine efficiency and be noticable at the engines top end, would you put cheap parts on your MX 5? if you can afford the better fuel then go for it.
I found a marked difference from premium & super petrol when used in my Kawasaki W650, it ran much sweeter with super at all speeds.
I didn't see any noticeable improvement using Super in my Mark 1...
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