Correct fuel type for Octavia RS

[woofy]

Yeah somewhere after 2008 98 became a bit selling no no, as Mazda dropped the 95 requirement for the 6 to 91.....which no doubt has led to lots of problems down the track as 95 has higher QC. OUr Mk2 has 98 and when the Mk3 comes I may as well just keep using 98 as I think the 95 may have been a marketing ploy. Or I could be wrong and its actually tuned for 95...hard to beleive though.

[woofy]

I guess the engine has changed from my older TFSI so if they can now run more power on 95 rather than the 98 my current one needs than its pointless running 98. I've had pinging/diesel knock with the Caltex vortex diesel which I thought would be a good idea to run as its only marginally more than the low grade diesel, so using the Vortex 98 probably makes bugger all difference on the Mk3 if it ignores any octane higher than 95.

[Gerrycan]

A few random thoughts:
I think the new Ford Focus Ecotec 1.6 turbo and the Hyundai new turbo ranges are designed for US low quality fuel and they claim quite high outputs and are able to run on 91 Octane. Goodness knows how they do that.
Apparently all Australian official fuel consumption tests are required to be run on 95 Octane (not sure what is done with regards to those cars requiring 98 Octane?).
Finally, I have yet to see a properly run test that proves there is substantially better performance running an unnecessarily high octane.
I am excluding those dyno tests for tuned engines.
I remember the old Shell tv adverts of my Pommie youth where car "A" with Shell always ran 5+ mpg better than car "B" with the competitors product. The advertising focus now is more on the better detergents in the higher grades will keep your engine running cleaner/better/more economically. Might be something to do with more truth in advertising required these days (Fatblaster apart)?

[Tuan]

Doesn't answer all the questions but a but good read nonetheless since it's an actual real life scenario

Unleaded vs E10 - the comparison test | CarsGuide

Once your car is tuned, it's a different story ... best to stick with 98 (and some tuners swear by BP Ultimate).

[Gerrycan]

I am afraid that article is typical of its type. The general background info is accurate but the methodology of the "test" is so flawed it makes me cringe.
I drive a particular short (13 km) urban route in Adelaide and on the same fuel (even on the same tank) the consumption can vary by over 100% depending on traffic and environmental conditions. My best is 4.2 L/100 and worst is 8.5 L/100 and both were driven with an eye on economy. The higher consumption was probably the better effort because I had to use the air conditioner and traffic was terrible. The lower consumption was at night, but I still had to stop at 5 red lights so I could have done even better with a bit more luck.

Unfortunately Julian Edgar at autospeed.com has never done a fuel type comparison (that I can find) but his home spun testing methodology for his car mods (economy and performance) is about as good as you can get outside a laboratory.

[Tuan]

Which part of the test makes you cringe ?

[brad]

Which part of the test makes you cringe ?

Using suburban running to test fuel consumption.

There are too many uncontrolled variables. The only way to do it properly is using a rolling road.

[Gerrycan]

Which part of the test makes you cringe ?

Brad got it in one.
Using a rolling road would eliminate the majority of the variables but even then some care has to be taken to get accurate results.

Of course if you want a real laugh then watch the 'infomercials' on "Today Tonight" or "A Current Affair" on tv when they get on any automotive subject.

[Tuan]

Look at what VW managed to do with their emissions testing in a controlled environment..

I do see the point in doing it in a lab/rolling road but we don't live/drive our cars in a controlled environment so a real road test in a daily driver gives good enough information for me.

[brad]

Look at what VW managed to do with their emissions testing in a controlled environment..

I do see the point in doing it in a lab/rolling road but we don't live/drive our cars in a controlled environment so a real road test in a daily driver gives good enough information for me.

trying to compare fuel consumption using different fuels by driving in the suburbs / open road is like trying to compare cakes that have been cooked in different ovens.

eg: Do test 1 over a 4 week period in January & test 2 over a 4 week period in february & test 3 over a 4 week period in July. The differences in fuel consumption would be significant - esp the jan feb tests.