Recent post in off-topic: http://www.sr20forum.com/showthread.php?t=128922

I was thinking about doing this in my Neon to see if it actually does enhance mileage. Should I be concerned about fouling something up in the fuel system (ie injectors, pump). What about the valves, pistons, O2 sensors, etc.? Thoughts?

http://smileys.smileycentral.com/cat/new/8_22/4_12_12.gif

Here's a start to better education (http://www.bu.edu/es/labsafety/ESMSDSs/MSAcetone.html)

According to this (http://www.hcdoes.org/airquality/webpages/EIS/VAPOR.htm), acetone has lower vapor pressure than even low RVP gas, so that's good for emissions. Slightly tougher for cold starts, but fuel injection does wonders in that regard.

Has an enthalpy of 1821 kJ/mol. Compare with most hydrocarbons in gasoline at ~4600 kJ/mol. Much lower energy density. That damned oxygen molecule hosebags acetone just like it does ethanol and MTBE.

Neither my sources nor the Internet reveals acetone's octane rating, so no comment other than oxygenates tend to have rather high ratings.

In all, I'd expect acetone to behave like any other oxygenate, meaning higher octane but poorer fuel mileage due to the low energy density.
You can go to any hardware store and buy quarts of acetone with which to experiment. Don't anyone DARE post results of one tankful, though, or I'll personally track you down and fill your tank with diesel.