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Originally posted by Cursa
PanaceA, I gotta disagree wi your economy figures. I get consistently more mpg with 97 as opposed to 95.

You get less miles on a tenner because you get a smaller volume of fuel, and your car seems to be using the same amount of each fuel in each pulse.

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PanaceA, I gotta disagree wi your economy figures. I get consistently more mpg with 97 as opposed to 95.

You get less miles on a tenner because you get a smaller volume of fuel, and your car seems to be using the same amount of each fuel in each pulse.

superbikes really benefit where they redline about 13,000 RPM

Not just for Jap cars, The recommended RON for my Dad's Porsche is 98

oh, i use optimax which is 98RON i think

i have noticed that my 1.2 not only idles better, but is improved throughout the rev range, more noticeable when cold, also i have found it more economical after 3 tanks

97 RON is the octane level of the petrol. The higher it is the more aggressivly it burns. Standard petrol is 95 RON but you can buy 97 and 98 RON from many petrol stations. The 97 and 98 RON petrol is sold mainly for performance Japenese cars like Imprezas. In such a car the engine would perform a hell of alot better with the higher octane petrol. In Japan almost all petrol is 100 RON so when you buy a Jap import car you HAVE to run it on high octane petrol such as 98 RON or performance will be greatly reduced. Rally cars also use high octane fuel, WRC fuel is 102 RON!
Putting 97 or 98 RON in your car won't make much difference, it will probably make you car a touch quicker but I doubt you'll be able to feel it. It makes more of a difference in turbo charged cars and, like a said above, in Jap performance cars.
Another thing with higher octane fuel is it burns up quicker, I can do 70 to 80 miles to a tenner of 95 RON in my Punto Turbo where as with 98 RON I will only make 60 - 70 miles on the same amount.

[Edited on 26-05-2003 by PanaceA]

I get more mpg in my 99 sport. Difficult to say if performance is better, but i wouldn't say it was worse. My car has an automatic knock sensor, you might need to turn over a plug under your bonnet to adjust your spark timing.

Would i actually see a drop in performance by putting 97 RON petrol into my car or would it be exactly the same performance but just cost me a bit more?

I realise you can get a special plug from the dealer but i still don't think it improves performance.