Just picked up an 06 3500 4x4 crew cab 8 ft bed w/cap. Anything out there that will help with mileage? Trans already rebuilt. 233,500 miles. I pull a trailer 8-9 months out of the year on a daily basis

I have a 06 2500 4x4 Megacab. I installed the Diablo Tune In ALL 4 different settings and checked my mileage by dividing gallons used by miles driven (over head mpg indicator is off by as much as 5 mpgs). Guess what? No improvement. The overhead indicator says it's better but it lies.
I keep mine in tow haul mode where it adds 60 hp and about 100 ft lbs torque. Truck feels whimpy when I put it back to stock.
I have gone to max level which adds 180+ hp and 200+ ft lbs torque and truck is a beast.
I bought mine for better mpg which did not happen. I'm addicted to the extra power so I'd buy one again.
Best mpg empty is 20. Best mpg with 3750 lbs GTX in enclosed 24 ft trailer is 13 and best with TWO GTXs on a 32 open trailer is 15mpgs. Power to spare. Love the truck.

Hand calculated im only @ 10.5 mpg. most of that is towing a 10000 gvw trailer with 2 zero turn mowers on it. best on hwy was 11.4 on a 30 minute drive @ 60-65. any idea why my mpg is so much lower?

My mileage numbers are towing Florida to Georgia or North Carolina, so mostly flat land and several hundred miles each way. Towing I like to run at 70 mph. The sweet spot for economy is 1800 RPM. Mine has 3.73 gears and 33 inch tall tires.
Fuel economy drops real bad at faster speeds. At 80-85 my fuel consumption is 15 to 16 mpg.
Does your truck have the 4.10 rear?

Mine runs about 13.5 at 70-75 towing a 9500 lb. 5er (Atlanta to PCB, FL- pretty much like mercman1). Empty is 16-18 city ( if I keep my foot out of it) and as high as 22-24 on the highway ( if I keep it at 1900 rpm- about 70 mph) but it's hard to do if you run with the flow of traffic. Mine is stock down to the tire size and I'm considering going with a taller tire to lower my rpms on the highway. I had thought about a tuner from a mileage standpoint but everyone has a different answer (other than raising HP and torque ).



Tim

I have a smarty Jr on my 06 mega cab. I didn't notice much mileage gain with power level settings, but did notice an improvement when the timing was advanced. My EGTs were also a tad lower with a more advanced timing setting, and also takes less pedal input to get moving from a stop.