Does HHO really work?  Ask all of the people who have decided to make their vehicle an HHO car and see what their answer is. They will tell you that they have a lot more money to spend on the things they want, since they are not having to spend nearly as much on gas.  They will also tell you that they can beat a lot of cars off the line at a green light because their car has more horsepower.  And they will also tell you that they are helping the environment because the emissions from their HHO car are cleaner.  And they will tell you that tax time is not quite as brutal for them, because they get a tax break for driving a hybrid.