Petrol Octane Rating And Performance

[MrT]

Has anyone any noticeable experience of using different petrol octance rating and performance?

 

My Galaxy handbook recommends using super unleaded as compared to ordinary unleaded for the best performance and economy. I have used both and to be honest I cannot notice any difference in performance or economy, except it costs more to fill the tank with super unleaded.

[Richmond]

From a completely unscientific assessment, I think that the super gives if anything fewer mpg for no increase in performance (and is of course pricier). The performance with regular is fine anyway, too good for the suspension etc. With the amount of petrol the V6 gets through, the extra cost of super is psychologically impossible to cope with.

[seatkid]

Seen a wiring diagram on another ford model (can't remember which) that has an "Octane" plug, evidently used to set the fuel octane for the PCM. With it being a VW engine maybe its programmable via VAGCOM.

[Richmond]

My handbook, and I expect MrT's, says that either super or regular can be used but that super will give best performance and economy. I'm not convinced. Even if super does give better performance, it would be wasted, and the economy would have to a hell of a lot better to offset the extra cost of super.

[MrT]

Exactly what my handbook says.

 

I would expect that the engine management would detect any "knocking" as a result of using lower octane fuel and adjust the timing and injection accordingly.

 

However I have not been able to notice any difference in performance or economy by using different fuels and I was wondering if anyone else had noticed any.

 

With my cynical outlook it would not surprise me if the same fuel came of the the two different pumps at the filling station.

[wiggybn]

I keep a close eye on my mpg and I cannot see any improvement on 98 octane. I've tried quite a few times in France where the price difference is very small but still can't see any benefit.