Isn't adding hydrogen to gasoline the normal way of increasing a gasoline's octane? So it seems that it's just giving you high octane fuel, though not sure if this is going to help diseal truck engines.
But if the system can be cheap enough [7k is too expensive for cars] and can vary octane level [mostly increases octane] then it should be a good thing. If nothing else, it can turn regular gas into premium gas [or even higher octane than premium].

I think you could simply use stored hydrogen [thereby lowering the cost] instead of making the hydrogen, though I imagine there is some efficiency in using using the electrical power of alternator during long cruises [different matter in stop and go traffic or climbing hills].