The 3.0 CRD is at peak tq 1k rpm faster than the ecoboost. 1500 vs 2500 rpm. I average 27 mpg with my 07 Grand Cherokee 3.0. That is a mix of 50/50 hwy /city driving in the summer. It does have a tune on it. When stock it got over 22 mpg with the same driving. This is in a 5500 lb vehicle with full time awd. The transmission is a 5 speed, put an 8 speed tranny behind it and it will only get better. The 3.0 engine has been around for a long time in the European market and is a proven engine. It is not nearly as quick as a GC with a hemi, but put a 5k lb trailer behind both and it would be on equal ground.