I would strongly encourage you to get a hemi, not much more cost to upgrade but they seem to go for about 2 or 3 times as much at auction a few years down the road so much higher resale value as well as more fun to drive and the MPG is barely worse in the real world than a V6. You may spend a couple hundred more in fuel over say 5 years but the re-sale value will easily be thousands more (and easier).
The Hemi was a $3,795 option in 2015 in the Durango, $3,000 in the 300. I think it's gone up to $4,000 now? Highway mileage is really good @ 22 ~ 23 MPG. Wife (avoids hwys at nearly any cost) driving in town is almost painful, ~ 12 - 14 MPG.
