I have stuck primarily with 93 octane fuel, various brands, but have tried 89 octane a few times. Following is the Octane vs. Trip Computer MPG vs. Calculated MPG for several tanksfull (similar combined city/highway driving):
Octane--Comp. MPG--Calc. MPG
---93-----------------------16.00
---89-----------------------14.05
---93---------15.8--------15.37
---93---------16.1--------16.20
---93---------16.1--------15.55
---93---------16.7--------16.18
---89---------16.3--------15.81
---89---------15.1--------14.58
---89---------15.4--------15.01
---93---------15.7--------15.36
---92---------15.7--------15.33
---93---------15.7--------15.70
---93---------16.0--------15.23
There's not really enough difference to shake a stick at, and I noticed NO performance differences, nor did I notice any pinging with the 89. I am currently using 93, but I'm not sure why when I look at the figures.
Octane--Comp. MPG--Calc. MPG
---93-----------------------16.00
---89-----------------------14.05
---93---------15.8--------15.37
---93---------16.1--------16.20
---93---------16.1--------15.55
---93---------16.7--------16.18
---89---------16.3--------15.81
---89---------15.1--------14.58
---89---------15.4--------15.01
---93---------15.7--------15.36
---92---------15.7--------15.33
---93---------15.7--------15.70
---93---------16.0--------15.23
There's not really enough difference to shake a stick at, and I noticed NO performance differences, nor did I notice any pinging with the 89. I am currently using 93, but I'm not sure why when I look at the figures.