Yep along with all the suckers that are building these idiotic things worldwide.
It goes against the laws of physics. No matter HOW you try to split water into its two components it takes more energy to do than you get out. Even if the engine was 100 percent efficient (its about 30) and the alternator was also 100 percent efficient (its not) and you didnt need wires (you do) then it still wouldnt work. Because the power needed comes from the alternator, which has to be driven by the engine. The greater the amps taken out the more work the engine has to do. And the more fuel it consumes. This is due to EMF. Turn on the lights on an old carburettored car and the motor slows slightly. This is because it really needs more fuel to drive the lights.
The hydrogen/oxygen gas helps offset some of power needed to produce it that but mostly it just wastes some energy and results in LESS mpg even if everything was 100 percent efficient. And its not!
There are a lot of people getting rich over this scam due to peoples ignorance of basic physics. If it actually worked you could build an over unity generator! You woulsnt need a fuel tank. Just a bigger HHO generator...
And you could build big power stations that ran off HHO and fed their own furnaces powered by themselves!
All you are actually doing apart from resucing mpg is wearing out your alternator faster, adding weight and complexity and making someone rich and watching some bubbles.