[invader]

I use 91/93 when I can. I'm rather sensitive and perceive the engine to run just a bit smoother across the range. Torque around 2k is slightly improved, not by much. Most of the time I run 89 due to cost. Being in a hot/humid climate I don't run 87 as the engine stumbles under accelleration.

Interesting to note if you look in the Lexus UX200(not H) owners manual on page 464 it says very plainly to use 91 octane or higher for "optimum engine performance. Those cars have the exact same engine as the Corolla (dynamic force models only). Now it is entirely possible that Lexus has a different tuning from the factory as they know their customers tend to have deeper pockets and won't care, but I have a feeling that these cars can benefit from it.

Fuel economy wise, I get the best on 89. 93 I'm a little more aggressive and burn through any gains I might get.

 

[invader]

Tier 3 (88 pump octane) vs Tier 2 (93.3 pump octane) as tested by EPA on 2018 Camry 2.5 A25A-FKS Dynamic Force engine.

Benchmarking Advanced Low Emission Light-Duty Vehicle Technology | US EPA

Brake Thermal Efficiency

For the Toyota A25A-FKS engine, the high load transient zone was limited to a narrow band near peak torque, and differences between initial and final values of BTE were minimal, except for small areas at low and high speeds near the peak torque line. BTE using Tier 3 Fuel: The Toyota 2.5-liter A25A-FKS engine was also benchmarked using Tier 3 certification fuel (see Table 4 for the fuel specifications). After mapping the engine on Tier 2 fuel, and prior to collecting engine data on Tier 3, the engine and ECU were pre-conditioned by running through the full engine mapping process with Tier 3. This allowed the ECU to adapt to the change in octane and alcohol content across all its low to high loads for approximately three hours. Data was then collected by running through the mapping process a second time on Tier 3 fuel. Figure 27 shows the effect of changing fuels on BTE at 2000 rpm and 3000 rpm. All data points shown in Figure 27 are at stoichiometric air fuel (A/F) ratio; higher load points that include commanded fuel enrichment are not shown. The steady-state mapping results show very small BTE differences between the two fuels below a torque of about 160 Nm. It is important to note that the minor drop in BTE observed with Tier 3 fuel does not actually correspond to an increase in CO2 emissions because Tier 3 fuel has a lower carbon content than Tier 2 fuel. As described previously, using Tier 3 fuel results in a small-but-measurable overall reduction in CO2 both on a fleet-wide and individual vehicle basis. This is also true for the Toyota 2.5-liter A25A-FKS, as installed in the 2018 Toyota Camry.

Here is the link
Benchmarking Advanced Low Emission Light-Duty Vehicle Technology | Vehicle and Fuel Emissions Testing | US EPA

I'll attach the two report.
Tier 2 Fuel is equal to 93 (RON+MON)/2
Tier 3 Fuel is equal to 88 (RON+MON)/2
View attachment 332369 View attachment 332368
Here is the BSFC & BTE charts

Tier 2 fuel(93):
View attachment 332365
View attachment 332366
Tier 3 Fuel(88):
View attachment 332367

From the report we can see when using high octane rating fuel, the efficiency will be higher in high rpm high load region.
The fuel enrichment on knock suppression also is slightly late compare to 88 ratings.(Might means more power?)
The spark timing is also shifted a little.

EPA already did a test for High Octane Rating Fuel in Dynamic Force Engine | Toyota Nation Forum

 

[invader]

I recently purchased a 2020 corolla se 6mt and I am curious about what would be be the optimal octane of fuel for it. I feel like 87 is to low for a 13.0 to 1 compression... Any insights.

91 pump octane is absolutely perfect for it.