Looking for some real world numbers from guys that drive 2500HD's with the Duramax. What kind of mileage do you get? City - Highway - Loaded -Unloaded I am trying to justify the added expense of the diesel. I definitely do not need the added pulling power but I WANT it really bad! Please no replies like "my buddies dad says..." or "we took one on a trip once..." I am looking for numbers from guys that own or have owned one long enough to know the mpg under varying conditions. Thanks!