That looks impressive and in line with the EPA rating of 21/23/27 for the 3.0L diesel on
https://www.fueleconomy.gov/feg/bymodel/2024_GMC_Yukon.shtml
Yesterday, tom3 on this forum reported the average of 23 mpg on a 500 mile trip with his 5.3L Tahoe and he hand checked the readout. That's quite a bit higher than the EPA rating of 15/17/20 for the 5.3L gasser.
And there are tons of mpg reports on this forum that vary quite a bit.
I would like to know how much money I would save on fuel, PER YEAR, with the Duramax vs 5.3L Yukon assuming that I don't drive much, about 5,000 miles a year mostly city driving. So I made a spreadsheet using EPA mpg and AAA current national average fuel prices of $3.53/gal for Regular and $3.85 for diesel.
My annual fuel cost would be $1177 for the 5.3L gasser and $917 for the 3.0L diesel. A savings of $260 per year if favor of the diesel. Or $220 if I subtract about $40 for the DEF fluid.
Frankly, if I'm going to drop $90,000 for a new Yukon, I don't think $20/month would make much difference. Even if I go with the 6.2L and burn premium gas ... I'll forget about the mpg and focus on more important aspects of the diesel vs gas, me thinks.