I was just going to post this same question. My truck has a 26 gallon tank and I ran it from full, to low fuel (usually takes about 22 gallons to fill back up). Since installing the tune and reseting the fuel used, it only says I have used 15 gallons on a whole tank which makes my MPG eneriously ...

I recently purchased a Predator U7186 and I have heard you can download\purchase off the internet software for another compadable Duramax without buying another predator? Just wondering. I have only had it on my truck for a day so I will have to update my experience.