brown gas
n.— «Besides saving gas money, using what is called “brown gas” makes the car drive smoother, cleans the engine and is better for the environment, Bogue said.…Under his hood, Bogue filled six quart-sized jars with water and baking soda, covered them with vacumn-sealed plastic lids, installed a charcoal filter and connected it all with tubes to the car’s air intake system.…Besides saving gas money, using what is called “brown gas” makes the car drive smoother, cleans the engine and is better for the environment, Bogue said.» —“Baking soda boosts mileage” by Karen McIntyre-dn Daily News (Red Bluff, California) May 7, 2008. (source: Double-Tongued Dictionary)
Further reading
If you alternate alcoholic beverages with glasses of water over the course of an evening, you’re said to be zebra striping. This bit of slang was inspired by how the animal’s alternating black-and-white markings are like the contrast between the...
In White Oleander (Bookshop|Amazon), novelist Janet Fitch touts the value of memorizing poetry with these memorable lines: Always learn poems by heart. They have to become the marrow in your bones. Like fluoride in the water, they’ll make your soul...
Still a scam. It takes more energy to make the gas than it gives off when burning.