I found this, along with many others:
"As a mechanical engineer, I would highly recommend NOT adding acetone to your gasoline. Check out the following link to compare the compatibility of acetone and gasoline with various materials:
http://www.coleparmer.com/techinfo/chemcomp.asp
Note their compatibility with this material in particular: Buna-N (nitrile). Note that it has "excellent" compatibility with gasoline, but it will have a "severe effect" with acetone.
Why is this important? Because most seals and o-rings in fuel systems are made from Buna-N. A small leak in your fuel system could lead to a big car-b-que on the side of the road."
Whether it's true or not, it still sounds risky. I know acetone will literally melt/fuse plastic parts together. The amount might be a very low percentage but what about length of time acetone exposure to the car's plastic parts within the fuel system?
Here's link to a forum
acetone/gas
More topics on acetone/gas in
google