For some reason I couldn't open that pdf. I would like to take a look at it.

That's the first document I've ever heard of suggesting that E85 has octane as low as 94 or 96. During my initial research, I found a lot of references that had pure ethanol at 113 octane.

The non-linearity of blending is a big problem for me. I've got a spreadsheet that I use to figure out the blend, and it is a straight line linear calculation, so I could be off.

Another big problem is the variability of E85 itself. It's really E70 right now. Come April, it will briefly be E79, and then it will be E83 through the summer. It is never really E85. My spreadsheet takes this into account, but I can never really know exactly what is in the tank. I just assume that E85 is 100 octane, regardless of the actual ethanol content. I should probably make an effort to adjust that a bit based on real ethanol content.

I do have the ability on the Scangauge to see timing, so perhaps I can use that to get some idea of if the timing is being retarded or not, which would give some indication of the true octane.

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'02 X5 4.4i