I suspect you're leaving the conversation because you can't prove me wrong. Here's what I suggest: go buy yourself a tank of hydrogen, hook it up to your car and get it to run, and then devise a method to refill this quickly and conveniently. Do this, and then come back here and continue the discussion about the practicality of hydrogen as a combustion fuel.

But before you go to all that trouble, let me give you just a little fyi. You see, unlike you, I've actually worked with this shit in the past doing plastic brushing. I've actually handled hydrogen. The stuff is violently explosive, extremely flammable and completely odorless and colorless. It also burns with no visible flame. Leaks are about impossible to detect. A standard size 300 steel compressed gas tank is about 5 ft tall and about 10 inches in diameter and weighs about 132 lb. At 300 bar (4500 PSI) this tank will hold maybe a kilogram of hydrogen. A kilogram of hydrogen is equal to about a gallon of gasoline in pure energy. So you can start to get some kind of idea just how much hydrogen you would actually need to drive your car even a short distance assuming you could devise a system to deliver it... Which I'm assuming wouldn't be too difficult because it would be similar to the natural gas delivery systems which are in fairly wide use in the trucking industry right now, and which have been around for decades. I actually had a van years ago with a dual-fuel CNG conversion. Total pain in the ass. Huge tank hanging underneath gave a range of maybe 120 miles. Only one place in town to fill it, 20 miles away. Took it all off and threw it away. So there you go. There's your Dunning-Kruger epic.