They is no power differences stock unless recommended. Only time you notice the differences 87 vs 92 is luging the car out of a corner turn 2-or 3 gear and not down shifting, or the same slight up hill, pressing the gas and the car the car not picking up as fast, slight detonation, pinging,hot, this will Destroy your pistons. higher Octane help take away this knock more at lower speed. as ethanol is really a higher alcohol additive.( and our source of cheap unhealthy yummy corn syrup)
economy car drivers will gas it no matter where, so small engine are not advance to much. Lugging a engine as above need torque, larger engine have, small engine don't at all.
( you could also try a throttle valve spacers or having a longer one made, this also give torque, I use to extend the carb intake runner longer on my engines way before manufactures 1994 Most performance engine are tune for high octane. the danger is luging the engine for better mpg, but the tradeoff higher rpm mean more gas. if you build torque, lower rpm power. they is no danger of detonation as you have lower the power curve, my more torque added, engine and cvt has even pick up that creep forward a normal transmission does, let off the brake and will do it on a slight up hill. as stock it didn't.
learning to hear the slight danger pinging on luging as it's more pronounce when hot and easing according is the key.