Acetone as a fuel additive

[aldive]

there be a hidden reason for the 2 to 3 mpg boost?
.

There could indeed be such a reason.

Possible ones are:

(1) very dirty fuel system and it cleaned it.

(2) inaccurate mileage measurements.

I have tested acetone for a couple years and never saw that large an increase. I did see about 1 MPG boost, but not always.