If you could bring up a display of what the ignition timing is doing as you drive, like so you could see when and how the timing graph is showing in regards to the amount of retardation from the pre set one set, then you will know if you should need a higher octane.
All that a engines does is retard the ignition timing if it detects a slight ping and bang you can loose 12 deg timing and that kills fuel economy and fuel economy.
Most new cars should be using 95 octane and the car company's are only spinning crap about using 91 just to sell the car, back when the new 179KW 5.0L VT V8 commodore came out Holden claimed to use 95 but then did a back flip because people spun out that they had to fork out 4c a litre more, so they said just run the 91 it's fine and it is, but on a hot day or if you are up it that ignition timing retard comes in killing power and fuel economy badly, this eng could cut the timing by 2 deg segments all the way to 12 deg in all, but the earlier 5.0L 185 KW with the knock sensor just came in and wacked 12 deg out directly if it pinged.
I would think that if the timing is retarded then ADR would or could more likely not be passing the laws as it should be.
