Owned two First Gens and three Second Gens.......best one of the lot did 16mpg with 3.54's and a 60hp Edge chip. Additionally, I deal with a ton of people that run these trucks and they all get the same mileage as I did.

The odd person who needs to justify the 50 grand they just blew on a Cummins and 45 cent a gallon more for diesel will claim 20 to 35 mpg like a few on here, but all of us true Diesel Guys know they are full of it. There is also that other faction that after getting 9mpg out of a 454 or 460, and now getting 15mpg out of a Cummins feels like winning the lottery. Yes, a 50% improvement over a big block gas is huge, but it sure as hell isn't 32mpg like some of you have claimed on here in the past.

Guitar, you might as well add the house you were pulling behind you at 80mph and got 22mpg and ruin your credibility with me too.

Real World Cummins Fuel Mileage