There are a number of myths about the octane ratings of gasoline. In actuality, octane ratings only tell you one thing: the amount of resistance to detonation the gas has. But what does that mean?
That just means that gas with a higher octane is less likely to detonate before the spark plugs fire. Sometimes gas does that, like if your car’s engine has a particularly high compression ratio, the fuel/air mixture in the cylinder will get compressed so much that it may just combust, without any spark. That type of premature detonation, is called “knocking”. Sounds filthy right? It is.
Knocking can do some damage to your engine. It gets the engine working against itself, and can cause all sorts of problems. The thing is, it’s not going to happen for more than a second or so. All modern cars have a “knock sensor”, which is a little microphone that senses the actual sound of the knock and adjusts your compression and fuel mixture to stop the knock.
Most cars get absolutely no benefit from premium gasoline AT ALL, but some high performance cars have a higher compression ratio, and they can benefit from it. But they don’t need it. Because of the modern knock sensors, even high performance cars with high compression ratios don’t need premium gas. You won’t get the maximum amount of power from the high performance car if you use regular, but you’re not going to damage your car.
So the bottom line is: premium gas, for 90% of all drivers, is a complete waste of money, with zero benefits. For the small percentage of people who have high performance/high compression cars, premium gas will help you squeeze out that top shelf performance, although it’d be difficult to feel a difference.