True water injection was used in piston aircraft engines that ran turbo-superchargers. it's purpose was to lower combustion temperature and suppress detonation, allowing higher boost pressure and thus more take-off power...

As Caddyman stated, water injection is used for extracting maximum power from an engine without inducing detonation. It is not used for increasing gas mileage.

As to the "bio-diesel" claim, unless Mr. Gentile has actually put a purpose-built diesel engine into his Hummer, this would seem to indicate that he has converted the GM gas engine to run on diesel. While this can be done, the life of that engine would probably be very limited, simply because a diesel engine needs to be designed from scratch for that purpose, with much stronger and heavier construction than a gasoline-powered engine would have.

And, then of course, we have that pesky detail of "the equivalent of 38 mpg".
I am highly skeptical of Mr. Gentile and his claims.

"...unless Mr. Gentile has actually put a purpose-built diesel engine into his Hummer, this would seem to indicate that he has converted the GM gas engine to run on diesel."

The H1 was available with several diesels, including a couple of turbocharged engines. Of course, that makes the mileage claim even more difficult to believe. Are you sure it wasn't 3.8 MPG? ;-)

I think we're talking about a REAL Hummer, which is a diesel-powered vehicle, not the GM versions, which are pale imitations of the real thing.

What does "the equivalent of 38 mpg" mean? It either gets 38 mpg or it doesn't. My guess is it doesn't.

I just Goodled Tom Gentile and the first thing listed is "Rip-Off Report." That's enough for me.

It's on the internet.....it must be true.

Oh, yeah, I forgot. Sorry.

A Hummer that gets "the equivalent of" 38 mpg.

OK. Where can I buy one?

That is what I want to know.

Well, my friend, you go ahead and buy one. I'll wait to hear from you about the mileage.

Your original post was in jest, right? You don't actually believe this garbage, do you?

A Hummer that gets 50MPG is still an overgrown, obnoxious shoebox on wheels.

Of course you are correct, but for those guys who feel extremely insecure about their masculinity, those Hummers apparently represent Nirvana.

And that says what about the people who feel it necessary to point that out? :)

In this case, it says that the person pointing it out comes from a background as a professional counselor, and that he is quite familiar with the characteristics of men who are insecure about their sexuality.

I know an H1 owner and he is not insecure. It's his toy, and he likes it. He also likes his NSX.

Nobody said 50 mpg. 38 is the claim. BS, I'm sure, but nonetheless, 38, not 50.

Maybe this will help you understand my point:

A Hummer that gets 377MPG is still an overgrown, obnoxious shoebox on wheels.

Real hummers come with diesels. And run-flats. And even rocket launchers if you'd like. The only thing you could not get was 38 mpg. They were designed to traverse and invade the environment without regard to its condition, not to protect it.

Even the name, Tom Gentile, sounds phony.

The water injection thing makes it sound fishy (or should that be smells fishy).

I drive a diesel and I average about 50 or more in the city. So no, my opinion would not change if it were true. I still think of them as ego-maniacal capitalist-pig polluter who didn't care about the environment melting ice-caps and Polar Bears?

It's utter bunk and they're no doubt figuring fuel mileage the same way the Ford guy did on an 87 Mustang GT. He claims to be getting 110 MPGe with the 5.0 V-8.
Rather than help Ford out of their financial woes and become a mega-billionaire, he chooses to sit on a gold mine and won't let anybody look under the hood or have the car tested.

Note the small "e" on that. It means equivalent which then means it's whatever you want it to be.

You should keep in mind that water is very corrosive to aluminum and an engine won't last long with a steady diet of water into the combustion chambers.
Water injection was used sparingly on some WWII fighter planes. Even then it was only used during Full Military Power and only for seconds.
In other words, when a pilot had to extract himself out of a dangerous situation.

It doesn't seem possible that a full size SUV (even with diesel) can get the same mileage as an economy car.