It is claimed that a small unit installed in the fuel tank can save fuel 20-30%. The basic principle is reducing loss of volatile compounds via negative charged air. I really doubt the principle.

(1) To my knowledge, high voltage or radioactive material are needed to ionize air, but neither of them is used.

(2) Even without this device, the loss of volatile compounds can be up to 20-30? It does not make sense to me.

But the result of our test shows that it seems working. For a same route, 19 Liter gasoline is needed without the device and 12 liter gasoline is needed with the device. This is only one test so there must be some uncertainties. But I am really curious will it really work and if it is worthwhile to test more?

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    How large is your sample set? I'm extremely surprised at your results, because those devices don't actually have any provable physical effect. This post probably even belongs in Skeptics SE... – TDHofstetter Sep 1 '14 at 14:01
  • I'm with TDHofstetter here - these devices are a waste of time and money. I really hope the device DOESN'T do as claimed, as introducing a charge into the air in the tank would significantly increase the risk of an explosion! – Nick C Sep 1 '14 at 14:23
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    What is the question exactly? And using less gasoline without the device seems like it is causing problems, not improving fuel economy. – dobey Sep 1 '14 at 15:13
  • Sorry for the mistake in the question. More fuel is consumed without the device (19 liter) in our test. – user2230101 Sep 1 '14 at 15:56
  • Why is this downvoted? It seems to be an honest question, and I think it's pretty interesting... – Cullub Jul 4 '16 at 18:46

In the past, in UK government departments I worked in and for, we tested all manner of claims for such like devices and others on all sorts of vehicles. None of them proved in the least bit viable. The only differance that could be accounted for was that drivers tended to drive more considerately(less fuel consumption) in the vehicle knowing that they were there and had cost them money. It really is in the mind. The tractive effort required to move the vehicle will always remain the same, as will the calorific value of the fuel, which provides the energy to overcome the tractive effort. The only truly effective fuel saver I know of is a block of wood under the throttle pedal :-).


Total and complete snake oil. As @AllanOsborne said, there has been many conclusive tests done on these "theories". It's complete bunkum.

Besides, driving the same route and achieving a negligible difference in economy - without accurately measuring throttle position, engine load, etc - is just going to leave you with a biased placebo effect. You would need to have the vehicle on a dynamometer and having the engine in as controlled an environment as possible, like this: https://www.youtube.com/watch?v=VGtImIP6j3A

"Driver mods" are the only way to improve your fuel economy, realistically speaking.

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