I seem to remember a device I saw on the local news about two years ago, that uses hydrogen to increase FE. The news channel, ran some independent tests of their own, as part a consumer report they do regularly, and they did see improved FE on some vehicles.
(they have a video from the news cast I watched on their website)
After searching long and hard I finally found the device and wanted to strike up a conversion about it.
I'm as well off buying a carbon fiber hood, saving that 100 pounds is more likely to do something.
Same money, 500 bucks.
I can even direct you to a place that conveniently crossed out the higher price and has 499.95 on sale specials right now, yup, for a carbon fiber hood.
Some hype but they weigh about 20 pounds, no argument it is lighter than OEM.
Before I do that even, I'd get light weight racing seats for $60 - 100.
A FE gauge should be standard equipment in every vehicle.
After quite a bit of research I finally made the jump into this arena. No one could positively tell me that this technology worked or adequately disprove that it would not. As an Aerospace Engineer/Pilot/Mechanic the theory surely seemed to have merit so I purchased and tested one of the units on a 2007 Toyota FJ Cruiser. What I found is that the unit DOES work!!! I initially saw increases of approx. 3.8mpg (that's over 23%!!!). Now the frustrating part...the emissions system on the Toyota tends to revert to a default setting when it see's what it considers abnormal mixture settings & thus tends to richen the mixture to the point where no benefit is derived. This is most likely due to the 4 O2 sensors (2 heated) and modern Mass Air Flow (MAF) sensor which are sending the info to the onboard computer (ECM). There are additional devices out there (MAP/MAF/EFIE enhancers) which FOOL the ECM mixture but I'm not about to hack into the wiring of a NEW vehicle. After speaking with the manufacturers and other users, I've found that a number of vehicles (especially European, Nissan, and many GM/Ford) have responded quite well to the system. What makes this unit different from others is that it does not inject HHO (Browns Gas) into the intake, it separates the Hydrogen & Oxygen and only ports the Hydrogen into the intake thereby eliminating a lot of the excess O2 being injested into the engine and consequently remaining in the exhaust where the O2 sensors pick up the levels and instruct the ECM to richen the mixture. It does NOT take massive amounts of hydrogen to affect the combustion of the current fuel/air mixture so don't be fooled by other units. I've since re-located the injection port on my unit to see if the hydrogen may have been affecting the MAF, so hopefully continued increases can be maintained without having to reset the ECM. Note: once installing the device it is best to reset the ECM, usually by disconnecting the negative battery terminal & then hitting the brakes for about 30 sec (I suppose this internally grounds the ECM to clear it's flash memory)...this way the car will begin to remap the fuel/air ratio using the included hydrogen. Again, I DID see positive gains but this would not be true on vehicles which use performance chips to maximize the fuel intake or in cases where excessive throttle responses are involved. Essentially the unit allows the existing fuel to burn more completely in the chamber thereby increasing its overall effectiveness and reducing wasted fuel. I hope this helps!