How much of the savings was just from adjusting the computer so the engine is running lean?
An easy way of testing this is to dump the whole electrolysis set up and just use a hydrogen tank to inject it directly into the engine. That would set a maximum on the performance of any hydrogen system, which would be reduced once the engine's power has to be used to produce it.
You can probably get a significant mileage improvement by adjusting the computer. Your car's computer is set to make you pass your emissions tests, not for max mileage
Karl, you are right on the money, and this prof is typical: book accurate, but missing the point.
What they are doing with these systems is to trick the computers into leaning out the long-term mixture...or, allowing other devices to trick it without making the engine ping.
Problem is, the ECMs will allow 10-20% lean adjustment before they decide that something is wrong and flag a Service Engine Soon light.
So the prof is right that you can't violate laws of thermodynamics...but that's not what you need to do to have an improvement.
Oh..but car companies CAN'T do this and optimize only for fuel economy (1) for valve reliability, and (2) because ultra-lean mixtures will fail NOx EPA requirements!
HAHA! LOL! The EPA is blocking better fuel-economy because of emissions concerns.