The Stupid Will Always be Among Us.

The internet pretty much guarantees it:

Then we took the car to a specialist who installed, for nearly $1900(!), a hydrogen generator and a system of other enhancements. There was a fuel heater, fuel-line magnets (which I debunked here), and several inscrutable boxes full of electronics designed to fool the car's computer into using less fuel. There was even a bottle of acetone to add to the fuel. (This is something that I've mentioned doesn't work here
and here). The specialist guaranteed major improvements in fuel consumption.

One week and nearly two grand later, the producer from NBC (who still hadn't identified himself as anyone except a guy who was tired of spending $50 to fill up his tank) picked up the car. He got a gas receipt proving the installer had seen 96 mpg, nearly triple the original economy. We took the car straight back to that same EPA lab for another round of testing. It was followed shortly by a week's worth of road testing, dyno testing and general poking about to see what we could discover.

You can guess, right? The total improvement in fuel economy after $1800 plus of expenditure? Bupkis. Too small to measure. Nada. In fact, if you look at the EPA tests with the system switched on and then off, there's a tiny increase in fuel consumption when the system is turned on. I attribute this to the 15 amps or so of current the electrolysis cell consumes to produce hydrogen.

Darn those facts; they can be such a buzzkill when you are prone to believe in something for nothing.