I have been reading for while that the HHO add on for vehicles improve gas mileage by 20% to 50 % . Is there any truth to this?
The type of devise Iv seen make the hydrogen and supplies it to you air intake or air cleaner box , thus adding a volatile mix of air to the combustion chamber. 
Try Water4gasforum.com for info and answers.
or www.fuelbyh2o.com ( my link )
Consider it takes about 3200 Cubic feet of Hydrogen to equal 1 gallon of gas
and that any hydrogen produced by these systems is made by electrical power generated ultimately by the gas in you tank
and that the few bubbles of hydrogen these systems make is a long way from even a few cubic feet
and that at each transisition of energy storage methods there are losses …
You decide if it will increase your mileage.
Me - I am at the point that I just want to punch out the next person who tells me hydrogen is the most abundant element in the universe. They always seem to forget it is usually connected to some other element like Oxygen and it that it takes a lot of energy to separate it. Can you name any source of pure hydrogen found in nature??? I cannot!
For more info check out
[QUOTE=Longez;5042] Can you name any source of pure hydrogen found in nature??? I cannot!
[/QUOTE]
It’s free floating between the stars, all we need is a big hydrogen ram scoop. Geez man, don’t you read Heinlen?
what i think happens in this conversion is that when th ehydrogen is bubbled out and goes into the intake it also takes a bit of water vapour with it and this is the equivalent of the old water injection systen.
the addition of hydrogen to the gas going into the combustion chamber would not make as much difference with out a bit of water added.