Its really sad actually, that a pickup truck, with a small diesel, can't do a whole lot better, than a Class 8 tractor, with a diesel twice its size, and twice its weight. My buddy has a 379 Pete, with a 3406B cat. He towed his 46ft boat to loto, got somewhere in the area of 10mpg. In my Mack semi, I used to get 8-9mpg with an empty flatbed, with a total weight of 30k lbs empty. Loaded up at 80k lbs, It would drop to around 6-7.

Just found all my old notes,,,,,Dans truck,,,,, 2005 8100 Dually with 4:10

Non towing 13.5 at 65 MPH

Towing BZ's snowmobile trailer from Chicago to Houghton Mi 10.2 at 65 MPH

Towing 42 Fountain from Chicago to Louisiana and back 8.1 AVG,,,,, running 70 minimum

All dash calc

I wonder if the tires he switched to are hurting it that bad????/

08 F450, 6.4, 4.88's, RCD 525 Tune, DPF del, 37" Tires on 24's...truck scales @ 12k unloaded with me in it = 9-10mpg.

Towing 42' Fountain Ex on Myco only drops it to 7-8mpg @ 65-70mph average (have seen as bad as 6.6mpg). All hand calculated. Truck fully loaded scales @ 26k.

Truck, boat, trailer, and skank are all for sale....lol.

Trl505 get some tunes from gearhead performance. You'll like them much more than RCD.

Hmmmmm?? Ive had zero issues w RCD tune. Never head of Gearhead. Ill have to look into it.

I had the RCD 525 tune in my last truck. Was very pleased with the performance. I towed with the "450 tow" tune but never checked mileage.

2011 GMC 3500 4x4 DRW Denali 6.6 duramax
H&S Black Maxx, delete, cold air intake. Everything else stock
HOT setting (OMG fast) empty 77mph 1800rpm 20-21mpg
towing8-12k 77mph 11-13mph
Mild setting (about 50hp) empty 77mph 1800rpm 18-19mpg
towing 8-12k 77mph 10-12mpg
If I drop down to 65mph (which takes forever to get anywhere) I can up my empty mpg to 22-24 and my towing mpg is around 14-15

I know my numbers seem unbelievable to some, but they are straight up fact hand calc numbers............This truck with a programmer and bs removed is the best truck I have EVER owned period. It has 80K on it (it had 33k when I bought it in Dec. of 2012)
Around town I average 17.5 empty.

These trucks with the tuner,s on the hottest setting will give the best mpg as long as you keep your foot out of it .

I first had the RCD 525, the gas pedal is like a light switch. Your either on it or off it. Lots of smoke. Gearheads takes that away & virtually smoke free. I believe its yielded the highest numbers on the dyno as well.

Buy a lottery ticket !!!!