The Big Three's New Diesels put on a Dyno

Chevy has a 6 speed Allison and probably has most frictions loss through it but it's a proven work horse. I never cared for comparisons. I know the new ones are all troubled one way or other. What if anew Chevy engine had tighter tolerances than the others. Use more fuel! It's not true that higher HP makes for higher fuel consumption. My Duramax, turned up to 410 from 360 gets 1 MPG better pulling our TT.
Duramax engines have a water cooled intercooler.