I still think the 'swill' comment is funny... it panders to the marketing. The difference between 87 and 93 octane has nothing to do with the purity of the gasoline or it's quality, simply the trimethylpentane and heptane mix. Most people who yack on about octane ratings don't even know what they are.
True. Octane is a misunderstood beast. People saying it makes their car faster, are generally experiencing what their motor was actually capable of all along. It's not an enhancement beyond that, which was somehow bestowed by the magical high octane gas. Generally, it takes about 100 to 500 miles of varied driving for a vehicle to even readjust parameters in the PCM to different fuel anyhow. I suspect in most cases, filling up with 93 octane has a placebo effect more than anything else.
My view is a bit skewed I guess as I like to tune engines for fun and occasional profit. For me, there is no point in tuning an engine if it isn't running 93 octane as a baseline. The difference in the power and efficiency that some engines can produce running on higher octane fuel (to me at least) is quite amazing. Air/fuel, duration/advance can be pushed much further with the elbow room that higher octane brings to the party. My air/fuel bars are flatter the higher the octane. I'd run the 110 octane race stuff if I could find it for less than $9-11 a gallon with any regularity.
Stock 2008 5.7L HEMI advertised as 345hp (at the crank)
Added RDP CAI before test; tuning via Diablosport CRM software.
87 octane untuned rear wheel 296hp (Dynojet) 26mpg MDS active
87 octane tune rear wheel 307hp (Dynojet) 27mpg MDS disabled
Add 180 degree thermostat for tuning
93 octane tune rear wheel 324hp (Dynojet) 29mpg MDS disabled (Roughly 380hp at the crank if measured as advertised)
Add a mild cam and we go to 349hp, JBA & Corsa exhaust 368hp, polished/ported heads... but that's a different thread...
The gas doesn't magically make it faster by itself, but merely allows you to make the engine more efficient if you choose. Many cars have some advanced tuning metrics built in and require the higher octane sauce to make use of it. Many also have higher compression or are non-naturally aspirated which also require increased octane to both prevent detonation, and to cycle larger than normal advance curves based on the driving conditions.