Originally Posted by snrusnak
Realistically, the new hemi with mds gets the same highway mpg as the 4.7L (give or take)...the 4.7L probably should get a few points better in the city though. There's a lot of factors though... I just averaged my worst tank this weekend since I've had the truck (nearly a year). I got right about 16mpg average. Half tank of normal to and from work city driving, and half tank of city driving/idling as I was helping someone move this weekend and left the truck running for the wife sitting in the cab (it was raining all weekend while we were moving). I usually average about 18mpg. 17-18 city, 20-23 hwy depending on speed. Probably 95% of my driving is city driving.
The only thing I don't agree with in your statement is the oil change duration, if you're willing to go 8k miles on the 4.7L, why not the 5.7L?
I was a gearhead back in the late-60's and early 70's, when Hemi's were something really, really special...and quite rare. While there's many more on the road today, they're still something "special" in my old mind, and if I had one I know I'd fuss over it like a mother hen. Rational? Probably not, but I know I would. Also, I've read that the Hemi must use 5-20 oil; otherwise, the MDS won't work correctly. Now if the MDS is that
finicky about oil, I don't think I'd be comfortable going 8K between changes...even with synthetic. Based on what I've read, I don't think many Hemi guys are going more than 5K.