yea, you don't buy a Durango for the fuel economy. Properly set up, you should be seeing about 14MPG in 4x2 setting on that 1999.

IndyD

 

yeah, I think the best I've gotten is like 14.3 on the highway... and I still have a plenum gasket to replace at some point.

 

Best I've got was 19 on the highway. It seems like it gets better mileage at the 55-70 range and above that it drops down to about 13-14. I average about 15-16 between the highway and city driving which I don't think is bad. I knew it wouldn't get any more than that before I bought it, the Durango I sometimes drive around, but less now that I have my own (mom and dad's 99 with the 5.2) got a little worse mileage than mine, and it has the smaller tank, so it really seemed like it burned through a tank, so mine seems like it gets better than it does.