the professor on Gilligan's island made a coconut shell/husk burning engine

(these are/were actually very popular at one time) There is a lot of unburnt fuel in the husks/smoke that works quite well when pressurized in the combustion chamber of an engine. (though are more similar to a steam engine or old hit miss than a modern ICE type engine.)
I have heard a lot about the hydrogen generators as well, it must me passed along over C.B. as the trucker I know have been talking regarding it and asked me about it as well. my answer was similar to what was posted, it may actually work, but as far as increasing mileage it is doubtful as law of diminishing returns comes into effect way early... that 1600% seems like it may be close

, lots of inefficiencies in ICE and adding more inefficiencies making electricity then using it to make the H ~O2 fuel means more losses. but perhaps O2 probably what helps more than the H does. Will it help enough?? not sure I have not read any actual scientific discussions regarding it, it may actually help somewhat if the car/truck is already WAY messed up with a rich condition that needs more O2.
more than likely it will help your alt go out earlier & waste a bunch of time & effort is all...
I'm willing to bet that if you already have a gas guzzler that is running rich it may actually help it out a bit if you were to add pure O2 with a bit of H tossed in as well..
Mark M