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
Enthusiastic book recommendations! Martha’s savoring the biography of Alexander von Humboldt, the 19th-century explorer, polymath, and naturalist who revolutionized our understanding of nature and predicted the effects of human activity on...
A retronym is a word coined to distinguish something new from an older, more generic version, such as electric guitar or clock radio. A couple of new retronyms are fine water, or “unprocessed water that reflects a region’s terroir” and water...
Still a scam. It takes more energy to make the gas than it gives off when burning.