Seems too good to be true.
It is (too good to be true). Hydrogen embrittlement has been a very difficult anamoly in metallurgy for millenia. Fundamentally, hydrogen is the smallest element, and hydrogen ions can needle their way into any metallic matrix. This gives rise to dislocations and reduced strength in the materials exposed to hydrogen. Inducing hydrogen embittlement is enhanced at elevated pressures, temperatures, and strain rates,...i.e. conditions within an internal combustion engine.
Essentially, spiking the fuel with hydrogen is the opposite type of fuel desired by engineers. Formulated hydrocarbons, breaking into smaller components, allows the reaction products to also not be as volitile, and more stable in the engine system. On the flip side, the larger the products, if not simialr to the outside environment, naturally creates different types of pollutants.