Here are the results of my testing with Acetone from 11-1-06 through 3-9-07.

MPG
21.99 Winter Diesel (No Additives) 13.186 Gallons of fuel
22.46 Winter Diesel (Added 2.5oz Acetone) 13.804 Gallons of fuel
21.59 Winter Diesel (Added 2.5oz Acetone) 10.327 Gallons of fuel
20.13 Winter Diesel (Added 2.0oz Acetone) 11.236 Gallons of fuel
20.96 Winter Diesel (Added 1.5oz Acetone) 12.932 Gallons of fuel
19.28 Winter Diesel (Added 1.5oz Acetone) 10.216 Gallons of fuel
20.83 Winter Diesel (Added 0.75oz Acetone) 12.049 Gallons of fuel
23.28 #2 Diesel (No Additives) 13.104 Gallons of fuel
23.52 #2 Diesel (No Additives) 11.439 Gallons of fuel

It's a wash. IF it did anything, it was small enough to be absorbed into the normal MPG variance between tanks. The best way to increase MPG is to not use winter diesel!

I don't have any leaks and the hoses have not noticeably softened or hardened since the testing began.