Hi, Tom - welcome to the site.
My comments are ... you've already concluded what I would have said: "
Non-scientific results"!
Ever heard the expression "extraordinary claims require extraordinary evidence"? Acetone falls into that category, because there's no solid science to support the claims made on the topic.
On top of that, tank-to-tank comparisons are too fraught with interference from other factors outside your control to be valuable as a way of measuring this kind of stuff.
Your own data proves this: your average range in "normal" use is enormous! 44 to "low 50's" (let's say 51). That's a
16% swing from the lower end!
I'd bet it's far more likely that there is some other, more reasonable, explanation for the difference you've seen than because of acetone. (Did you happen to read this take on the issue from a professional?
http://www.fuelsaving.info/acetone.htm )
cheers-
Darin