And you're still acting like a child. Just because you believe something, doesn't make it true. I don't care what you're dumping in your tank, there's no way in hell you're getting 25 MPG from a petrol-fueled 4.8L vortec in a 5600 lb truck, in the city. Hell, I don't even buy that you were getting 18 MPG in the city before you dumped some junk in your fuel tank. Fuel system cleaner doesn't work that way. Either you're running on smaller tires and haven't fixed the ECM to account for the difference, or your math is just plain wrong.