Google: Octane rating, knock sensor, ignition timing.

/thread

Using RON 97 for Toyota Hybrid cars is even useless since most of the torque comes from the electric motor. The engine is mostly for charging and less for power.

Google: Mazda CX5 Compression Ratio, Fuel RON requirement.

/Argument

Found this article on the web and we should be thankful that we are not residing in the US.
http://autos.yahoo.com/news/regular-cars-t...e.html?page=all

Actually the ECU will adapt very quick based on the feedback from knock sensor. To simplify, this is how it works: the ECU will take a step forward towards the knocking point in every combustion cycle until the knock sensor detects a knocking then it will take a few steps back in a cycle. After that it will take a step forward again for every cumbustion cycle until knock is detected again. This process will be repeating again and again.

How it adapts to a lower RON: it detects a knock and take a few steps back, then when the knock is still detected, it takes another few steps back until knock is no longer detected. After that it will take a step forward again in every cycle until knock is detected again and it takes a few steps back.

I've read somewhere before, probably on Paultan but can't find the article, it said that our fuel stations can have multiple type of fuel at the pumps without any problem or any additional investment. However there would still be some problem in term of keeping enough stock for the type of fuel that is most in demand.

Euro standard is indeed more for emission control but it also dictates a cleaner fuel requirement which will make your engine last longer and able to retain its power output better after a period of time.

This is what I meant before when I said the ECU will take a few steps back when knocking is detected and will take a step forward at a time after the knocking stops. Then when it detects the knocking again, it will repeat the same process. Just like sleepwalker said, if the engine is not designed to take advantage from high RON fuel, it won't be able to extract more performance from the higher RON fuel.