dholly
Platinum Member
At only 1300mi., I have an '06 2500HD Ext cab w/ LBZ Duramax and Allison 6-sp. getting 14-16mpg (heavy foot)/16-18mpg (light foot) in stop & go around town, and 19-22mpg on the highway. The best #'s come on flat road at about 60mph when the tach is <1500rpm just loafing along. Mileage starts dropping pretty quick once you get north of 70mph. Pulled my 7000lb carhauler and B7610 thru the hills this past weekend with a bed full of wood for 60mi. and saw ~13mpg without tow/haul engaged. It tows so much nicer than my '05 5.3L RCLB gasser did (R.I.P.), I almost wouldn't care if it got worse mpg! All mpg #'s are from the DIC, too lazy so far to hand calculate, but both city/highway mpg's have been steadily improving since new and I hope the trend continues. Also, from what I hear and read, the Duramax tuner chips and programmers do seem to help hp, tq AND mpg (1-2mpg combined on a stock truck), with the LLY and LBZ's getting the best mileage both stock and chipped. I'm waiting to see the new LBZ Edge Juice w/Attitude tests, and will definately be doing 4" exhaust and chip.