'04 GMC Regular cab 2500HD 6.0 4.10's Here is my milage history starting with MY first figureable tankfull.... 1) 10.53 mpg 304 miles driven 28.86gal 2) 8.94 mpg 246 miles driven 27.53gal 3) 8.31 mpg 256 miles driven 30.81gal 4) 8.92 mpg 274 miles driven 30.73gal So you can see, all these fills were allmost full tanks, all filled up to filler neck. The last two, the low fuel light came on. Thats all I have now, as I only have about 1600 miles on it. I was expecting MUCH better. Granted, most of these miles are towing my 16' open trailer (Just under 5,000lbs), and the others are hot-footing it around town on short trips. I was expecting the double digit milage to continue after that first tankfull. Guess I was wrong. It runs like a raped ape, so its not like something is mechanically wrong with it. Anyone else experiencing single digit milage like this? I would like to think that on a long highway trip, I could see 12mpg, but that may be it. I purposly DIDN'T consider a Diesel, mainly due to the stop/go, around town driving that I do. Think I may have gotten 12 had I got the Duramax. Any of you 6 Liter guys want to post your numbers?