This DIY gadget can be found in Malaysia too. If you are lazy to DIY, you can buy it at around RM 1,800 - RM2,000. I have friend selling it and he brought it in from Australia.
The theory is simple, it generates Oxyhydrogen from "hydrogen" generator. One small unit usually will draw about 20-30 amps from your battery depends on how much Oxyhydrogen you wan to be generated. The amps drawn from the battery is determined by the baking soda that was mixed into the water. The Oxyhydrogen will be injected into your intake, which means u need to drill a small hole there. The oxyhydrogen will help the engine to burn more efficiently and hence, using same fuel but travel longer distance.
We have tested on a diesel engine and we have 25-30% savings claimed. Some tuning on the fuel supply was done to reduce the power of the engine to get more mileage.
One MAJOR problem with this generator was, the Oxyhydrogen is in vapour form and it will corrode your engine components. We must add a water trapper unit along the piping to avoid any water/liquid to flow into the valve or cylinder.
Another problem is, if you have an o2 sensor located at the exhaust manifold, then its sorry to say that you wont be able to use it unless u do some tuning on the ECU. Alot of these sellers claimed that the o2 sensor cause any problem after installing the unit, but believe me, we tested and it wont have any petrol savings or maybe worst FC.
Anyone interested to get one unit, i might be able to get it for you. If you wan to DIY it, it wont be easy.
I can answer any questions if you all do have, as I have came across with this gadget and tested it. To clarify this, Im NOT the seller of this product. I'm the customer...to share my experience.