Well its a load of bull. Besides snake oil what do most usless infomercial type products have in common? MAGNETS! It is all about the magnets here. Because Neither carbon, oxyogen or hydrogen have magnetic properties, this device can't possibly do anything to the fuel inside the hose it clamps on to.
1. The website is very carful to avoid explaining how it really works (materials used, mathmatical representation, indipendant verfifiable tests). They just say it does. Not only that, in their FAQ they are asked if its too good to be true. They answer in a way that Isuzu Bob would be proud of: "t is hard to believe that a technology this good is not being used by everyone.
In time perhaps this will happen. With financial and Environmental pressures, it is hard to believe this technology is not used by everyone. However, millions of units have been sold as this product is sold in over 70 countries." (BTW i didn't misspell the "it" at the begining of the quote, they did!)
2. The device appears to be an RF choke. It costs about 4 bucks at radioshack. Judging from its size it is probably for Ham radio antennas, but i can't be sure. You can also find such devises on cords on USB cables, laptop power cords, and other devices that have very high frequency EM waves, making them suseptable to interfierence.
3. Anyone know of a general motors company? Last time I checked it was General Motors CORPERATION.
4. Oh yeah, In its tests page, it says Ford Motor Company tested them... yet the subject cars are a Dodge and a VW. Why would Ford try and prove a device would increase on OTHER manufactur's cars but noth their own.... Hmm....