So i was bored and browsing around online and started looking at just hydrogen....
Thanks to wikipedia....
"The theoretical maximum efficiency (electricity used vs. energetic value of hydrogen produced) is between 80–94%."
So this got me thinking.... That would mean i would only need a fuel (like gasoline) to do 6-20% of the work right? (probably closer to 20%...

) So... with an ideal/perfect setup my 12 gallon tank could be converted into a .72 gallon tank!! 3/4 gallon for a fillup!! sweet!

And then i wound up hearing something about someone oversea making a hybrid- its all carbon fiber and only weighs a couple hundred pounds and it uses hho cells and has a one liter gas tank. It gets 1,337 mpg apparently. Its only a one-passenger and its obviously little but maybe this might be something??