RON95 vs RON 97 Petrol: Does it really make any difference?

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To most car owners, the only difference between RON95 and RON97 petrol is the price. Some swear by RON97, claiming it delivers more power, while budget-concerned users stick to RON95. Which is better? Is the extra power a myth? Do you really save money if you use RON95?

What is RON?
RON is short for "Research Octane Number". It determines the fuel's ability to resist detonation. Fuel detonated pre-maturely instead of burned smoothly prematurely means wasted energy. You might hear a knocking sound when that happens. If too often, it's also damaging to your engine.

So, higher RON rating means better fuel, right? Smoother engine means better power, right? Well, yes, and no.

It all depends on your car

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In theory, higher RON rating "could" allow your car to produce more power. BUT, what type of fuel is your car designed for? If you car manufacturer recommends RON95, chances are your engine already performs optimally with RON95 fuel. You will not see any performance boost at all by using higher octane fuel. Most everyday sedans designed for economical driving fall into this category.

However, if the car manufacturer states that the "minimum" required is RON95, your car ECU is probably tuned to better utilize higher octane fuel. RON97 fuel could deliver better performance. But how much better? Judging by "feel" alone is not accurate enough. We could fool ourselves into thinking our cars deliver more "ummph" simply because we have paid more. The only way to know for sure is to put your car on a dynamometer (or "dyno" for short) to accurately measure its power output.

According the several experiments conducted by the popular UK car show Fifth Gear, performance fuel can and do produce better power on performance-oriented cars. However, the increase is merely around 6% in the best case scenario. On a 230hp car, that translates to a 13hp increase. A well-trained driver can indeed sense the difference. But you gotta ask, is it worth the extra money you're paying? At the time of writing, RON95 costs RM2.00 per liter while RON97 costs RM2.50 per liter. That's paying 25% more money for a 6% increase in performance (in the best case scenario!).

Let's say you are driving a 2 liter, 150hp car. The increase in horsepower, if any at all, when using RON97 fuel is about 9hp. First of all, most untrained drivers cannot even feel the difference. Secondly, we don't really need that extra power in daily sedated driving. The only time when every bit of power counts is when you are racing on track.

But wait, what about fuel economy?

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Another school of thinking says higher octane fuel can improve fuel economy. If a car delivers more power, it could accelerate and reach cruising speed sooner. A car is at its peak fuel efficiency when cruising. I conducted my own personal, not-very-scientific experiment on this by running several tanks of RON95 and RON97. I compared the fuel economy numbers and saw no significant difference. Even if there is, the mild improvement in fuel economy is negated by the 25% higher price of RON97 fuel.

Here's my personal conclusion: RON97 is an luxury item. I know for a fact that I can feel the performance improvement in my car when I pump RON97. But for 99% of my daily driving, I don't need that extra power. I seriously doubt anybody would need that.

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