Info from consumer reports, 3 fuel savers that dont work.

[chasgood]

They tested 3 gadgets that are suppost to save gas. None of them worked.

The Fuel Genie, $90, which promises more power and better gas mileage, is a plastic device with curved blades that fits inside the air-intake hose. The airflow is supposed to allow for better performance. But in our tests with a 2004 Toyota Tundra and a 2004 Dodge Stratus, we saw no significant improvement in performance or fuel economy.
The Tornado, $80, is a similar device made of stainless steel. It is the same product we tested for a July 1999 report, when we said it didn't improve power or gas mileages in two test vehicles.

The Platinum Gas Saver, $100, includes tubing and a plastic reservoir containing liquid. It is the same device we tested for our report in February 2001. You connect it to a vacuum line leading to the intake manifold. The manufacturer says that microscopic platinum particles from the liquid are sucked through the line, helping your car burn gas more efficiently and cleanly. In our previous tests, there were no changes in fuel economy after we installed the device in two test vehicles.

[SVOboy]

Yeah, I've seen this somewhere before but I never had the good thought to stick it up here. But I forgot about the water injection thing, mehbe that is something that should be put in that thread, as it spells bad news for that idea, V_V

[chasgood]

Well it looks to me after researching that the water injection is more for racing than saving fuel.

[SVOboy]

Prolly is that way, we can always see though sometime. Mehbe it revolves around timing, but I dunno.