The problem is it takes more energy to split the water molecule to generate the hydrogen than burning the hydrogen generates. In other words, chemically, if one were to truly find an affordable way to have an on board system splitting water, it would result in a DECREASE in mileage. Commercial Hydrogen stations have appeared in L.A., but they're burning natural gas to create the energy to create hydrogen--doesn't sound too efficient to me. Of the current technologies, the only way to make hydrogen feasible as a fuel is the use of nuclear power to generate the energy needed.