[Hersbird]

The Durango is the most aerodynamic those years and has a smaller frontal area. I would say the 4.7 v8 is the most efficient engine even more so then the v6. My Daughter has a 2005 4wd Jeep Grand Cherokee with the 4.7 and can get over 20 mpg but overall averages about 14-15 almost all city. It is a full time 4wd as well with no mods or attention to trying to get maximum economy.

2000 is when the Durango got the 4.7 instead of the old 318 or 360 v8

Fuel economy.gov lists a 1999 Tahoe 4wd 5.7 auto as 11/15 mpg and the 2000 Durango 4.7 4wd as 12/17. Those are both the new ratings, they used to be 12/16 Chevy and 14/18 for the Dodge.