That test about octane is good.
I used to race in a very limited class for engine mods. Most guys were spending money on the 110 fuel. We tested it against the pump 87 and the 87 made more power. The other kicker was fuel checks. We would buy 87 at the local AM/PM or whatever. Test it for specific gravity. Quick run on the calculator for the max tested SG allowed, a dash of 8-14% nitromethane, and right at the top of the scale. Never got caught! But my exhaust sure smelled funny and idled crisper than the rest of them! When I quit racing I told the others about the AM/PM fuel, and how the 110 was a waste of money. Never said a word about Nitromethane.