Can you use water 4 gas or fuel? The answer is a resounding yes! Many people are now using water in their engine to not only save tons of money on gas, but they are also seeing big gains in horsepower and the emissions that are coming from the car will be much better for the environment. Great news for all you "green" folks out there! Electrolysis happens inside the engine, creating a substance known as HHO gas or Brown gas. Tired of paying high gas prices? Then try water 4 gas or fuel!