A friend gave me a bottle of this stuff swearing it makes a noticeable improvement in gas mileage. It's called FFT Gasoline Blend Combustion Catalyst.
My default position on all these "Miracle In A Bottle" products is that they fall within a range from useless to potentially harmful to your car.
This site includes a link to a PDF file citing a study by the University Of Southern Maine reportedly showing test results on this product, though the product name in the .pdf is Diesel/Gas Go.
Supposedly they found a measureable improvement. I haven't followed up to verify that the University can confirm they published this data as stated.
Here's the patent listing for it
The website for the manufacturer doesn't greatly inspire my confidence
with claims like:
"Does your car run like it needs a $90 tune up? Run just 2 tanks full of FFT, and you won't need the tune up. FFT brings performance back."
I guess it reconditions plugs/wires and distributor rotors too?
Anyone have experience with or knowledge of this product?