I does give an indication for sure, but usage on a single tank is not gonna give a definitive indication of the change being due to your tweaks, or was the ambient air temp and barometric pressure more optimal last month? Was there a change in driving style? Etc.
Not saying you're wrong, more...
Yeah, I was wondering about the accuracy of the scan gauge, and how it stacks up to long term tracking of fuel use.
My current work hack tells me fuel usage. I've run out out of fuel when it said I have 30+km of range left.
Apparently, that's 30 km of downhill only range
I was having a discussion with my 20 year old a couple of days ago about octane ratings. His mechanic told him he should be using premium, but his justification for why didn't stand up to logic.
Found this from the Federal Trade Commission, among loads of other articles...