Well I haven't been able to do a mileage test yet, and it wouldn't be accurate since my girlfriend and I are off roading just about nightly.
But in 2 hours of off roading the other day (first and second gear up some pretty extreme trails, and hills a full sized 4x4 would never make it up without serious body damage) we didn't even use a 1/4 tank.
I'm guessing that we used no more 3 gallons, which is a big improvement from before the acetone.
We're both very impressed.
Plus my mom is using it in her Nissan Diesel pickup now, and she's got way more power. She's pulling up hills 1 to 2 gears higher than she could before.
There doesn't seem to be a noticeable fuel economy change in her truck though.