This stuff is nonsense.

Water injection in piston engines and jet engines has been around in aviation since right after WW II.

Water injection does cool the engine and allows higher thermodynamic pressures in both piston and jet engines - simply put, water injection was a means of increasing the power output, not the economy.  I have lots of hours pushing throttles on what we called "water wagons".  Early jet engines, like in the pre-G model B-52s and early 707s had water injection, as did the last of the big round piston engines in DC-7s and Constellations.  But water injection was horribly inefficient, and went the way of the Ford Trimotor fairly quickly.  Turbocharging a piston engine, or using fan jet technology in jets gets a lot more power and far less fuel burn than did water injection.

Personally, I detest any sort of accusation with no proof, or conspiracy theories with no proof, other than mere speculation or a scanty piece of "evidence" that doesn't stand up to rigorous scrutiny.

And, the story of the guy at the airport drag stip with the 100 mpg carb makes no sense either - supposedly a millioniare now hanging out at the drag strip with his "buds"?  I've got a neat bridge for sale, too.  Do you believe it just because some old guy says it?

But really, if such things are possible, which they clearly are not (you can never defy or change the physical laws of nature - it takes so much fuel burn to produce so much power to propel a vehicle so fast), where are today's smart guys who would jump on this like a duck on a june bug?  Really, all of the smart people in the world, of whom there are tens of thousands, are going to be murdered or bought off by a few oil companies?  Gimme another break, please.

Yes, tremendously high mpg numbers are possible in a very controlled situation - very small engine (note that the "engineer" interviewed admitted that these were lab experiments; not practical driving exercises), accelerating very slowly, and traveling at the peak speed for peak mileage, and geared very high, driven in warm weather on a totally level road that is silky smooth, and in no headwind or cross wind.  Not practical, everyday cars, but tightly controlled lab experiments.

Take any average size car today, put an engine in it of about 1 litre displacement, max; use fuel injection, take well over 2 minutes to accelerate it to about 40 mph, which is the peak speed for max mpg, and have it geared so high that about 40 mph will be top speed since the engine can't rev any higher due to the gearing, and you'll see 100 mpg.  But would you drive this thing in your normal travels?  No.

Anybody who falls for this stuff really needs to get real.  But then somebody falls for a ponzi scheme everyday too, don't they?