The Octane Rating of fuel references the fuel's resistance to burning. Contrary to common thinking, 87 octane gas is a lot more flammable than 110 octane racing fuel.

"Resistance to burning" also means "resistance to knock" or, technically, "resistance to premature detonation." This becomes useful when compression ratios are higher.

Compression ratios are higher because the efficiency of an Otto Cycle internal combustion engine increases with delta T (heat) and the more you compress something, the hotter it gets. At the extreme end, diesel engines run compression ratios an order of magnitude higher than your gas engine. You can drop a match in a jug of diesel and it will go out. Try it.

Essentially, high octane fuel is necessary for high compression ratio engines which tend to be high efficiency, high performance engines. If your car's manual does not specify high-octane fuel, you do not need to use high-octane fuel

UNLESS

Using regular octane fuel causes your car to knock when you accelerate up hill. This means that carbon deposits within the combustion chambers of your engine have raised the compression ratio above design. On the plus side, you're getting more oomph. On the minus side, you're getting more heat. And you need to buy gas that doesn't cause knock.

The manufacturer doesn't tell you to run 92+ for shits'n'giggles. They tell you to run 92+ because the engine is designed to run on 92+. If they tell you to run on 87 or better, run on 87. Or better if it starts knocking.

And that's about all I have to say about that.