Best Engine

The last two cummins I drove have not been worth any thing other than noise makers compared to the 96 CAT I had, and the 00 CAT I have now.
I know every body says cummins is better. But not all of em are!!!!!

 

Best mpg of the current big 3 is the Cummins ISX, a motor I don't like. The engine is efficient because it reduced upper engine parts and had less internal friction.

All of the engines have problems, some are due to driver error, some are due to them being mechanical devices, none of which are perfect. I was told that the N-14 shouldn't be revved over 2200 holding back on hills; I have driven Red Tops that would top that easily without breaking a sweat on acceleration, others wouldn't get over 1800-1900 no matter what. I drove older Cummins with or without jakes, the Detroits I have driven have been better motors overall than the Cummins, they may not have been the first up the hill but they went further on a gallon of fuel than the Cummins.
They also had less leaks despite the nickname for Detroits of Driptroit. On the same line, Cummins are Come-aparts, and Caterpillars are Crapterpillars

I would buy what I thought I could make the most money with, I don't care about how they sound, more about how they run.

The engine thing has been complicated recently by emission considerations and the fact that you might not be able to get your preferred engine in your preferred truck. Cummins considered Detroit competition and then stopped selling Daimler (Freightliner, Western Star, Sterling) Class 7-8 engines, but they are still selling them the smaller B and C engines for medium duty trucks.

Dealerships are specifying trucks that can get better mileage if they are properly driven, that means learning to operate the machine instead of just driving it. There is a Freightliner dealership pushing the C13 Cat in such a manner, it is lighter in weight than the big Cats and the way they spec it, if you drive it right, you can get better mileage than the Detroit can, or so they say. I don't know what will happen in the future, but any improvements in performance will likely be of small amounts.

Until the diesel sheds it's undeserved image for being dirty, we will continue putting up with regulators trying to clean it up even more.