I've been dumping acetone into my truck's gas tank for a while now and I'm happy to report that it appears to be harmless to the truck: no unexpected explosions, no stalling, no loss of power, nothing negative. I can definitively say that the acetone has not decreased my fuel efficiency, but I can not yet say if it has increased my efficiency at all. I'm going to run a few more tanks with acetone after I get back to Concord and my driving habits stabilize (drive to Cambridge, drive back, repeat a bunch). After I get a solid baseline of Concord to Cambridge runs with acetone, I'll do a few tanks without acetone and see if I can notice a change. In the name of science I will make a point of getting gas at the same gas station as much as absolutely possible.
I started my testing with 1/4 cup acetone per 15 gallon tank (~1.3oz/10gal), using acetone from a 1 gallon container of pure acetone that I bought at WalMart for the purposes of this experiment. Using the same acetone, I stepped up to 1/3 cup acetone per 15 gallon tank (~1.8oz/10gal) and continued to have no problems. I'm planning to step up to 1/2 cup per 15 gallon tank (~2.7oz/10gal) before I start doing my real data gathering. I may go up to 2/3 cup per 15 gallon tank (~3.6oz/10gal) after I get some solid evidence to support the effectiveness of acetone as a fuel additive.