 Hydrogen fuel enhancement from electrolysis (utilizing automotive alternators) has been promoted for use with gasoline-powered and diesel trucks, although electrolysis-based designs have repeatedly failed efficiency tests and contradict widely accepted laws of thermodynamics (i.e.conservation of energy).Proponents, who sell the units (often called "HHO devices"), claim that the dynamics are often misconstrued, and due to the chemical properties of the resulting mixture, it is possible to gain efficiency increases in a manner that does not violate any scientific laws.