Does Higher Octane make a difference?

[tiger862]

I accidentally put Exxon Supreme+ which is the best fuel they sale according to the ads
I knew something was up when I seen the total cost so I checked when I got home. My observation is power is better at low rpm. I tried midgrade which I got a little bit better fuel mileage but worse drivability so I went back to regular. I quit using econ mode as I had drivability issue I didn't like and was worse on 89. Now with premium for the last 100 miles econ mode is the same drivability as regular unleaded without econ mode. With regular unleaded it downshifted on slightest touch of pedal, midgrade held it to long and super it shifts smoother and at correct time. Perfect example is getting on interstate. Regular it will hold gear until you get about 5k, midgrade would shift at 2k and keep giving gas until it downshifted and hit 6500 RPM. Today with econ on (forgot to turn off) got on interstate and it shifted at 2500 then I gave it gas it downshifted to 4500 RPM then I didn't feel it shift again but I know it did. Is it worth it the jury is still out. Between econ mode (1-2 mpg) fuel (1-2 mpg) I am still little short from breaking even. I could be easier on accelerating but what fun would that be.

No difference between this tank and others. I got 18.7 compared to 18.5 and all points adjusted for transmission with throttle for best fuel mileage not best performance. To me if it isn't tuned for it then you throwing money away. I have flex fuel so this didn't make any difference.

 

[supton]

I can easily see how it's model dependent, and even then, usage dependent. The guy toodling along in the right lane, never more than quarter-throttle, might be fine with 87 octane in some super-duper car spec'd only for high test.

In the end, it's hard to argue with 3+ tanks of 87 and then 3+ tanks of 93, similar driving habits. Some won't care about the extra cost but will love the better response, others may only care about cost per mile.

 

[nicholas]

At one time Toyota used to mention that in the owner's manual with regards to the 1MZ/3MZ and 1GR VVT-i engines. "Minimum octane requirement of 87. But for increased performance use a higher octane"......not exact quote.....but along those lines.

My 2016 mazda 6 gt has this exact line in the manual.
91 performance is better than 87 and quite noticeable on very hot days.