I usually check with the Attorney General's Consumer Advocacy website if something comes up with claims that I might feel are outrageous, but nice if you can get it. This is for Texas, but I'm sure most states have some sort of consumer site. If a product doesn't work or has horrible side effects, it's usually documented there.
Someone I know began selling some really expensive magnets that were suppose to give better mileage. I was skeptical, but decided to give it a test run since it was on his nickel. I ran my 69 VW Beetle to Houston to deliver a gas tank that needed to be repaired. I did this without the magnet to get a base line on my mileage. I installed the magnet and went back to get the repaired fuel tank driving the same roads at the same time of day at the same speed. It came out 17 percent better mileage. I was shocked, but at first felt like maybe there was something to this.
Well, there are variables. You just don't realize how things can affect your mileage. I removed the magnet and made the same trip again and got 24 percent better mileage than the baseline which was better than the magnet run.
What happened? The Beetle had a 1600 dual port stock VW engine with dual Weber carburetors and no air pre-heat system of any kind. My baseline run to deliver the fuel tank in Houston was toward the end of winter and my carburetors were icing somewhat. When I went back with the magnet installed it was a little warmer. And the last run without the magnet the day was very warm. Temperature was affecting my mileage and therefore there was no way to determine if the magnet had any effect on my mileage.
Better to let the pros test everything. You just have no idea what may be affecting mileage. Wind, temperature or even a bad batch of gasoline can affect your results.
