Well, after a tank of fuel I can honestly say my millage has improved over 200%, my horse power has increased by almost 30 and my Mountaineer now makes a nice cup of espresso for me on the way to work in the morning...
OK - Maybe not... I haven't noticed any difference in the drive ability of my truck and there is no noticeable difference in mileage either. About the only thing different is that I didn't spend the 10 bucks on something worth while - like beer...
This stuff might work for a really bad running vehicle but - I really doubt it.