Yes, it did increase my mpg, but certainly NOT by double! Over the course of several months and probably ten to twelve tanks of Chicago city stop and go driving my average went up from 14.7 to about 16 mpg. Obviously adding acetone did not address whatever was causing such low mpg to begin with, but it helped a little.
From an organic chemistry perspective, the addition of acetone -- in the right proportions -- will increase the amount of fuel burned instead of wasted. It did for me.
Are their serious downfalls to using the substance such as hearing that the acetone solution may mess up the O rings/gaskets, fuel injectors, etc. in the long run. I even read that due to acetone having 5% of water may create rust in gas tank. trying to do as much research as possible, my car is 96, 154,xxx miles