Alot depends on many minor differences between cars, by this i mean, every engine is not identical in every minute detail.
My father in law owns a car yard, I have driven more varied cars than i've had hot dinners and found that every so often you get a car with what i call an exceptional engine, one comes to mind a vs wagon which regularly got 700 kays a tank long distance yet other vs commodores i've driven (gosford to lismore) only manage 500-600.
I've had same model cars respond more to higher octane fuels than others. I've had good batches of fuel and bad.
It's not inconcievable to get gr8 mileage on a car with higher octane fuel, but usually only on well looked after vehicles and/or ones that seem to have a very good engine.
I've pulled apart so far 80 engines in the last 10 years and you can tell the ones that were really well built from the ones that were average and you can also tell the ones that were looked after compared to the neglected ones.... What i'm trying to say is some people may have freak cars and engines that respond exceptionally well whereas most of us dont.
When you start measuring internally the differences between two stock identical engines and find that due to manufacturing tolerances that one has more compression ratio than the other, slightly lower deck heights, more closely weighted pistons etc than the other... it's not suprising to find one had far more power and economy than the other...
Then add in our geographic locations, air density on the day, elevation etc... the ecu fudges the ignition timings and fuel mixtures to keep a baseline seamlessly, different conditions yield different percieved power outputs and noted fuel economy...
Fuel is only one aspect of the whole picture
I'm tired, i guess i'm saying i take little stock in anyone who want's to go around saying this and that is a definate yes and no when it comes to whether or not higher ocatane fuel makes worthwhile difference or not. Too many varied factors.
My old EB Falcon Tow car felt constrained on 91 but had good economy. 95 felt no real difference but no change to economy. 98 it felt very willing but economy went poorly. Yet after driving a friends EB at the time, mine went a hell of alot harder and used far less fuel than theirs did when i had to use it for 3 weeks.
Engine components are mated by Wear. Made by man made machines, Assembled in an environment that has "tolerance" limits not "perfectely identical to exact specifications" Driven by human beings whom are all different, driven in different areas with different environmental factors.
If you feel like paying for 98 and it feels/seems to make enough of a difference to you in your car... fine use it... if not... well do waht you like.
I just dont like seeing a heap of people thinking this topic should be a "black and white" way of seeing whether or not the OP's point of view is valid or not seeing as it's all subjective in standard vehicles.
Bear in mind, none of this relates to vehicles built and designed specifically for higher ocatane fuels.
My vh ss has to run 98 due to engine mods requiring it (bored 40thou, decked 30thou with flat-tops). In the cheap run abouts i get around in... ... depends on the car's response to the fuel used.
To each their own
