All those 'hydrogen from water' and browns gas generators are a con.
You can never get the same energy out of burning the gas as you had to put into the system to split it into hydrogen and oxygen in the first place.
They appear to work really well for a short demonstration because the power needed is sucked out of the battery. Once the battery is flat then it all falls in a heap because the battery is recharged by the engine which is running on the hydrogen that is generated by the battery,.. which is recharged by the engine which is running on the hydrogen that is generated by the battery,.. which is recharged by the engine which is running on the hydrogen that is generated by the battery,.. which is,.. and so on.
If each step was 100% efficient then you would at least break even, but each step is inefficient so it quite soon flattens the battery and the car is again just running on petrol and trying to recharge a flat battery.
The idea is not new. It's been around for a hundred years.
It's always announced with much fanfare as some great new invention. Suckers flock in and hand over their money for shares in the company or to buy plans so they can make it themselves.
Some of them put one on their car and if they want to hit the headlines they announce it as a huge success,... and then it quietly fades away because it is all a big smoke and mirrors magic trick.
It doesn't work.
It never has.
It never will,
because the underlying principle is wrong.
The tried and true principle is, You get nothing for nothing.
If you want to amuse yourself then go ahead and do it but DON'T PAY ANYONE ANY MONEY.
{edit} I just read the article listed on that link. It was in June 2008.
Gee! If it was even half as good as they said it was you think they would have made a killing flogging it off by now.
I wonder why we haven't heard any more about it??
Oh,.. I know. Big Oil paid them a million dollars to shut them up?
I don't think so.