The difference is Einstein and Edison were pushing science and were working within the law of thermodynamics. Why must we try something that can't possibly work? That is INSANE! Must we try to turn lead into gold to know that it can't be done with current technology?
TRY reading for a change, some of us did! The following is stolen from the website DogHead cited:
Well the first thing is to work out how much energy it requires to keep an average vehicle cruising at(say) 65mph. According to this source it takes around 20HP to cruse at that speed.
Let's convert that to electrical energy by multiplying by 746 (the number of watts in a horsepower). We get 14,920, or roughly 15KW.
Now, if we want to replace 40% of that power with energy from HHO gas, we'll need to use at least 15KW x 0.4 which comes to 6,000 watts (6KW).
If we assume that the electrolysis cell which converts electricity into HHO gas is 100% efficient (which it certainly isn't) then that means we'll need a massive 6000W/12V or 500 amps of current to make that much gas.
Suddenly those 30A wires are looking rather inadequate aren't they?
What's more, since the average car's alternator can only deliver about 80A of current, this means the battery would have to deliver the other 520A and (in the case of even a good 80AH unit) would be flat in under 10 minutes.