Savvas replied:

Hi Tac,

The only way to substantiate for each vehicle is to try it for 4 or 5 tankfuls. If the amount of fuel you use drops substantially, then you might be at an advantage. Be aware though that at 9c/L more (upto 12c/L at some places), you do need to be doing better than a 10% reduction in fuel consumption for any benefit at the hip pocket.

However, there are other advantages to premium fuel and in particular the family of 98 fuels such as Shell Optimax, BP Ultimate and Mobil Synergy 8000 in that they do burn cleaner and help keep engine insides and fuel system cleaner than they would otherwise be with most standard unleaded fuels.

In my 2000 Jackaroo Monterey, I do not see a significant difference around town and certainly not enough to warrant the extra cost on consumption alone. I do see a significant enough difference out on the open road of around 10%. This is enough for me to use premium on long trips even though I'm only breaking even on cost. The extra responsiveness that it does provide is useful on the highway.

Hope this helps.

Cheers ... Savvas

Nudenut replied:

ditto saavas reply
I have 2000 GXL and I have not seen any difference in fuel economy
I am human ...I think?
Must be....make too many mistakes!

Davoe replied:

Been a previos thread on this. It is my understanding that when running normal ul the knock sensors in the engine retard the ignition to prevent pinging resulting in slightly less power and worse fuel economy how much? dont know but I had a housemate with a falcon who made the same claim. (have a deisel myself)

Jon - '88 TD42 GQ replied:

I drive a Diesel now but when I had a Crummydore I did try premium for a while. I did notice better power and response but never did anything that would quantify it. I can't say there was any noticeable difference in fuel economy based on the L/100 figure the trip computer gave me. Results in a newer car designed with PULP in mind may be better (mine was a 94).

In the end I gave it away. The benifits just weren't there.