Certainly the magnets have been around for decades.... they were one of the first things I ran across almost 40 years ago when I started playing with fuel economy mods. More often then not I was frustrated with results. They do seem to need to be rather powerful and direction does seem to make a difference. Over the years working with cnformation, mpg club, GEET, and BWT/HAFC I've heard of one guy that put them on his fuel lines, air intake, cooling/radiator hoses, pvc hose and even his ignition coil lead. He claimed excellent results and information was decided for him by a psychic... (his words/claims...not mine). fwiw he also warned me that while Pantone GEET could work to stay clear and be careful...perhaps I should have listened to his psychic?!
I believe it was when I with Pantone/GEET that we got data from another individual that had tested magnets extensively and claimed to have conclusive evidence that not only did the direction/poles facing the fuel line make a difference, but also the direction the vehicle was traveling! ..
As I recall the claim was that traveling North got better mileage and heading south it dropped slightly from factory...but overall mpg was higher. (This could be explained scientifically by something as simple as a change in elevation...ie: heading north going downhill and south was uphill).
I guess what I'm getting at is I'm an information junky. Love to read and here about it all but we need to research , test it scientifically and share the data. Many mods / devices have been debunked. Some I'm convinced do/or rather did work, but with new gas/oil formulas along with ever harder to 'tune/trick' pcms make it difficult to get gains on some of the newer vehicles.