Found this post on a Gran Turismo site in America.

Is this guy talking sense or out of his arse?

“The method of calculating octane for gasoline/petrol is different in the United States and Canada than it is in the EC. Europe's 95 octane fuel is roughly the same as what's refered to as 89-90 octane in North America, and European 98 octane stuff is roughly the same as the jurassic juice sole in the 'new world' as 92-94 octane.


Sunoco, an oil company that mainly serves America's midwest, offers 98 or 100 octane fuel that would be roughly 104 octane using the EC method of calculation. Good stuff, especially in summertime when it's not been oxygenated.


The cheapest 87 octane unleaded available in North America would be about 91 octane using EC guidlines.


The Japanese use a JIS formula to determine octane that (like JIS horsepower figures) is different yet again to what's the norm in North America or Europe.”

Any answers?

According to Rallysport magazine, the Italians have a 102RON petrol available. I suppose it would be required in the warmish land of the traditional supercars (ferrari et al).

I don't know if this guys conversions are correct, but it is true that Octane is measured differently in the U.S. compared to Europe.