The real solution to gas savings is to eliminate the need for gas completely by converting to a hydrogen fuel system. The way to do this has been found, it is very easy to do. There are many benefits. So that is the way to go.
One can do a complete conversion to hydrogen and they won't have to buy another gallon of gas.
Some people keep their "training wheels" on and do a partial conversion to a gas/hydrogen hybrid system. That is even simpler to do. And it will reduce your gas consumption, usually by roughly 1/3rd.
There are other steps you can take to better MPG that I felt I should mention here....

Pure acetone impedes evaporation rather than adding something to the fuel itself. So acetone is not actually fuel. You will benefit - very negligible amounts from about 1/4 of one percent to 1/3 of one percent. MPG starts to reduce at higher ratios.
Along with aiding MPG, Acetone reduces pollution dramatically and helps engine longevity. The optimum amount is approximately the same as 2 to 3 oz. per ten gallons and this will enhance mileage
about 25-percent or more. Your mileage will improve and your car will run better. You will achieve a quieter running engine to last longer by obtaining better vaporization and mileage . That tiny bit of Acetone reduce the amount of wasted gas to near zero.

One head's up ? Acetone is PAINT REMOVER so please use a small stainless steel measuring cup and long funnel to protect your paint. Acetone should not be bought from drug stores. Their brands suck being sold out there because they has been diluted with impurities . Good Acetone has that powerful Acetone odor. Canadian acetone is usually high quality. Go to a good paint supplies store

Again, the optimum fix is converting to hydrogen.
If you are not bold enough a full conversion as many already have, this tip about Acetone will help with your mileage after you do the hybrid conversion.