Originally Posted by PIPER-68
My 08 6.4 F450 dually with 4::30 gearing got about 6.5 pulling my 48' gooseneck with 14K on it and about the same empty . It really stinks .My 7.3 gets 10 or better doing the same thing . Wish I would have known how bad it was going to be , I wouldn't have bought it .I get really tired of the cummins guys telling me about 20 + .
Yeah, me too. But when I've driven a cummins I have got pretty close to what my psd does. However, I'm comparing unloaded driving for both and my sd has synthetic oil while the cummin had dino oil. syn gave me 2mpg instatly on my 07, not towing. I've been searching for years for some basis in fact for these claims without success. I would say if everything is equal, and remember the dodge truck weighs a lot less than an sd, the cummins does get 2mpg more unloaded. My last trip back from my farm in Oregon, 450 miles, cruise control, crc additive in fuel I got 22 at 60mph. That included crosses a couple of mountain passes and lots of hills. Hills are under 3,000 feet tall in my book.