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Just curious of people's expierences when tuning for economy if they had a better L/100klm figure with 98 or 91 octane fuel is the extra $ worth it in the end?
Feel free to post eng type and L/100klm figures

i haven't had anything that made the 98 worth the extra cost as far as economy, but for performance it was

that said i guess you have to think of it a bit differently, so you will get an improvement in economy but not enough to cover the extra cost, but then it will also give you better performance when flat out, so is this gain going to make you happy to spend a few more dollars per tank ??

I have a 2010 VE 210kw SV6, used the car with 91 ulp for several tanks always from the same fuel supplier, then filled with 95 PULP(no 98 PULP in town) the car gets approximately 100kms further per tank.

thats a good improvement!

i did a test with my mother in law a while ago, we were both heading to the same place, 300km of highway driving.

We both filled up at the same servo. Drove the same road one behind each other, both with cruise on, then both filled up at the destination.

Her car is a completely stock vs v6
Mine is stock but with extractors/exhaust, cai mace style box with pod, 1.95 rockers and a full tune, including tuning lean cruise for 15.4:1

She used 91ron i used 98ron.

I used 2L less than her for the whole trip.

I suspect if i used 91ron it would have been much the same, so performance upgrades dont always net more fuel usage, only more power, more right foot nets more fuel usage.

I previously owned a 3.6 VZ povo pack Commodore, tried both 91 ulp & 95 Pulp & couldn't tell the difference, seat of the pants or fuel consumption didn't change.

with my sv6 the only one spot i can feel the difference between 91 and 98 is in the overtaking. be cruising say 80kms behind a slow car and when get a chance to overtake, flatten it and on 91 it will drop back a few gears, then rev for a bit not really going anywhere then it will slowly pick up and go, do the same thing on 98 and it will drop back then just launch.

i've been meaning to have the laptop on it to log it but i suspect with 91 its getting massive knock retard hense the lack of response but with 98 it doesnt.

other than that i can notice when towing the race car 98 will be able to hold gears that it wont with 91, but thats an extreme case hehehe

Awesome responses guys, particularly like the1 test using cruise on a stock vs modified vehicle, I am conducting my own trial on my vt 5l this week usually gets 10.4L 100klms on 95ron std CJDN tune. I am now running 100ron united fuel that's 10% ethanol. I will Post my results in a week after I have finished tweaking the timing

Looks like I'm going to have to wait a few weeks to finish my testing as I have a crack in my exhaust before the o2 sensor and it's playing funny buggers with my AFR. And I can't get it welded till I finish working away and get home