Interesting thread in light of the recent fuel chaos here in the UK.
In my Z (and the porsche) I carry a bottle of Octane additive for those "just in case" moments when I find myself with no fuel and nothing available but the old E5... In these cases I used to put a minimal amount in, say £10, and then add the additive and then fill with super at the earliest opportunity. Not sure if this would be an option now on the E10 fuel?