I took the plunge today and added acetone to my petrol mix. I've read that it increases the octane level of the fuel, making it burn more efficiently. We will have to wait and see if it saves fuel. Noticeably, already, the idle speed has increased - so I presume the engine is running more efficiently without using any extra fuel. As for performance I haven't noticed any difference yet.
The only concern I have with acetone is that it could melt/dissolve any plastic or rubber components in the fuel system. I guess this would happen gradually over time - luckily I don't have a plastic fuel tank. Be careful not to splash any on paintwork - it'll strip it down to the metal in seconds.
I mixed acetone to petrol at a ratio of 1:400, which equals 25 ml per 10 litres of fuel. I used a cooking syringe to suck the acetone from the bottle, so I could read exactly how much i was getting, then squirted it as far down the filler tube as I could before adding the petrol. One word of advice - don't open the acetone in the car - the fumes are very strong - I had a head rush from doing this earlier. not good for driving.
Has anyone else used acetone - good or bad?