I just bought an 04' hemi limited and my answer was a former boss' $900 Altima. she couldn't take it with her and it has been in a garage for 2 years. It is loaded with leather and sunroof. The best part.......26mpg! Sometimes the cost of another used car (insurance, gas, and payment) may be less than the cost of gas in your Durango. It was for me. Good luck in whatever you do.
Taking it easy with the gas pedal helps a lot! I'm not trying to be snyde--I drive mine long distances and keeping the truck below 70 on the highway can really help... Taking it easy around town can make a big difference.
I honestly have hit 24 mpg (a very rare maximum!) on the longer runs (~300 miles) on the highway.... and as much as 19 around town. But I have also had fun with the thing and have seen 16 on the highway, and 9 around town! heheh! :rck:
Other than that--keep the air pressure in the tires up to what it should be, and change the oil on time/regularly... and I think she'll treat you right! :gr_patrio