Gasoline and HHO?

Why is it that the use of combined Gasoline and HHO converted from water passing through an electrolysis
doesnt seem to knock out the rising cost of fuel worldwide. if this would globally become a practice among car owners, even public utility vehicles, the cost of fuel would dramatically go down to a level most users will be capable of buying.  There seems to be less problems with conventional engines, so the use of this combination fuel o your cars would definitely save you money, and would raise the possibility of more people buying cars because of the lowering cost of fuel.
Governments should encourage the use of this technology because they can save a lot from their budget ant these saving can be used for a more pressing needs of the times, especially during this time of financial crisis.