Anecdotal evidence suggests that adding acetone to gasoline may increase mileage, but these claims haven’t been independently verified under scientific conditions. In addition, acetone is a solvent. It can remove the paint from a car or truck if it spills while being added to the gas tank; more importantly, it may eat away at the rubber gaskets and plastic tubing of a vehicle’s engine.
There are many compounds claimed to increase mileage in automobiles and trucks. They’re claimed to operate in different ways; acetone is said to enhance gasoline’s combustibility. Under normal circumstances, untreated gasoline is injected into the combustion chamber as a fine mist. Adding acetone to the gasoline is said to make the droplets in the mist finer, thus increasing combustion efficiency and gasoline mileage. Only a small amount is said to be necessary, about 6 to 8 oz. (177 to 250 ml) for a 20-gallon (75.71 l) tank.
Claims of acetone’s utility as a mileage enhancer are generally found on Internet bulletin boards, especially those appealing to car and light truck owners and similar sites. They’re often very credible because those making the claims aren't selling anything and clearly won't profit from anyone taking their advice. Indeed, acetone is commonly available in the US as a solvent used for a variety of purposes, including paint thinner and nail polish remover. It’s easily available and relatively low-cost — a single gallon of acetone could treat more than 16 tanks of gasoline at 20 gallons (75.71 l) each.
There are varying claims of the extent to which adding acetone will increase mileage. Some claims are relatively modest, at 10% to 15%, but the majority assert that they’ve realized mileage improvements of 20% to 30%. Even at the anecdotal level, though, there are those who report that they’ve seen no visible difference in their mileage after adding acetone to their gas. It’s important also to note that efforts by independent testing laboratories to replicate the claims have thus far been unsuccessful.
Gasoline mileage is a measure of a car’s efficiency that is more accurate the longer it’s measured. There are many variables that affect gas mileage, including outside temperature, winds, type of road, average speed driven, and so on. Thus, a car could get two significantly different mileage measurements on two separate tanks of gas. Some of those who’ve claimed increased mileage from adding acetone to their gas admit that they’ve experimented on only a single tank of gas so far. There’s also the possibility that they subconsciously adopt better driving habits while testing the acetone because they’re more focused on their gas mileage.
There are three main reasons it’s doubtful that adding acetone to gasoline can increase mileage. First, petroleum companies haven’t added it to the gasoline they sell. Acetone is extraordinarily cheap to produce and could easily be added to gasoline at the pump, if gas companies could demonstrate a mileage-enhancing benefit from it. Second, auto manufacturers, which have an interest in being able to help their customers improve their gas mileage, don’t recommend the practice. Third, given the wide array of products marketed as gasoline additives that are questionable in value, if there was any substance to the claims that acetone can increase mileage, some company would have tried to make money from it.
It’s frequently useful advice that if a substance isn’t known to be harmful, it’s worth trying out. Acetone, though, is a solvent. It will corrode the rubber gaskets and washers in a vehicle’s fuel delivery system, and if the system includes rubber or plastic tubing, will also attack their components as well. Mixed with gasoline in the quantities suggested, acetone’s destructive effect on engine components will be slow-acting, but the potential for serious engine damage is very real.