Stan Meyer did not invent the HHO kit. He said so himself.

The HHO kits sold online, plates in water with lye or baking soda, wired to your car's battery: not Stan Meyer's idea, and he said why in New Zealand in 1989. Electrolysis "did not comply the law of economics because it was a self-destructive unit and we had to add chemicals to it… So we had to come up with a non-chemical device." Why a booster can't pay: the engine turns the alternator (about half the energy lost), electrolysis loses more, and the engine burns the gas at roughly a quarter efficiency, so you get back about a tenth of what you spent. In 2009 a Popular Mechanics and NBC test found an HHO unit drew 15 amps and couldn't make enough gas to break even, and the FTC sued the seller of a "Hydro-Assist Fuel Cell" whose ads claimed a 2007 Honda Civic went from 35 to 85 mpg; the complaint called the claims false. Stan's claim was different: no chemicals, voltage instead of current, and the whole engine on water through his own injectors. Whether his process beat electrolysis is what builders are still measuring.

About the voices. The narrator is NeuralStan, an AI voice the archive uses for its made films. Where you hear Stan Meyer, it is Stan: every word of his is cut from an original recording, and nothing he says was synthesised.

Sources

• Stan Meyer · house meeting, New Zealand · 1989
• Stan Meyer, house meeting, New Zealand, 1989, part 1, at 21:28 and 22:05 — transcript on stanslegacy.com
• FTC v. Dutchman Enterprises (Hydro-Assist Fuel Cell), complaint, February 2009 — ftc.gov
• Popular Mechanics / NBC Dateline gas-saving device test, 2009 (as reported by Jalopnik and the Mail & Guardian)