Chet, I (and probably the OP) would be interested in knowing what your mileage is with that DEF system. That's the downside to the DEF systems is that you have to factor in DEF to your mileage, AND those systems severely decrease normal fuel mileage. To the point where truly the benefit of the diesel over a large gasser starts to get small.
My last tank was 15.17, EVIC said 16.43.
There are several things that are lowering my MPG at this time,I do some city driving,I also get on the freeway at WOT to merge,often this means going faster than a vehicle at speed.My trips are usually fairly short or up to 20 miles,I go over a 7% grade a few times a week,and this is winter fuel.
Last summer the EVIC was pretty constant at 18.8,I believe that was 2MPG higher than my calc.
On a longer trip I have had the EVIC saying almost 23 MPG.
On a similar interstate trip my V10 that truck used 3 tanks(35gal) of fuel where the Cummins used 2 tanks of fuel(31gal). The trip in the diesel was about 75 miles longer than with the gas truck. DEF is $13 for 2.5gal.
Not everyone needs a diesel, there are trade offs,that is why I say pick your poison.The last time I looked a diesel with 100K on it was worth more than a gasser with 100K.
My V10 was 300HP and 450 pounds of torque,the Cummins is 370HP and 800 pounds of torque,I do notice the difference going up a grade.I also like the E-Brake going down the other side.