I was trying to put some pure acetone which I just bought for 5 dollars for 32oz into my car, and i only had about a gallon of gas inside
You purchase acetone at $20/gal to get better mileage?
How about just buying more gasoline? You should get about 6 gallons plus. At least your travel range would increase without fouling fuel lines, filters etc.
But hey, it's your car.
But not for long.
Once the acetone ruins everything in the fuel system made of plastic or synthetic rubber including fuel pump diaphragm, fuel lines, connectors, fittings, seals, gaskets, and probably fuel injectors and various sensors, it will become the property of the local salvage yard because it will cost as much or more to repair it than a '94 Caddy is worth today.
This has to be the kookiest idea for improving fuel mileage I have heard so far, and there are plenty of those kook ideas floating around out there. For one thing, even if it doesn't ruin the fuel system vaporized acetone is probably more likely to explode than it is to burn when compressed and ignited in a combustion chamber, and when that happens a lot of very bad things happen to the engine's internal parts.