I can give you a really good idea. I have owned every cummins Dodge except a 12 v, and you can see what I drive now.
My last truck was a 2008 6.7 I got about 16 mpg hwy and 10 - 11 towing. When it was not in the shop. I even deleted all the emissions equipment off the truck so it would say out of the shop, and I just found other new issues like my G56 transmission and DMF.
My 2009 hemi on 87 octane (no corn juice!!) will get 15 mpg hwy and about 8 - 10 towing the same load about 8K lbs. I also have 3.73 gears, so if you got a power wagon you can expect less mgp for sure but I don't know how much less. It also pulls it without any issues at all. One thing is these motors like to rev up, but that is where there power is it is a V8 after all.
I had a ton of issues with my 6.7, and it was the biggest pile of junk I ever owned and I will never go back to a 6.7 again. My 5.9 cummins trucks all got about 18 - 20 mpg hwy and about 12 - 14 towing the same load, and by the way never had any issues with over 100K miles on each of them. They all had NV5600 or NV4500 manual trannys in them as well.
If you are not pulling a huge trailer eveyday then I would say away from any newer EPA loaded diesel.
I have only had my 2009 2500 hemi for about 6 months, but so far not any real issues. I have a whine noise in 1st gear, but some say this is normal either way it would be covered under my CPO. There is so much less to worry about with a gas hemi 2500 over a 6.7 I don't even no where to begin. The maintance on a hemi will be way less, and it will be in the shop a lot fewer times.
Last edited by evan4434; 09-30-2011 at 02:58 PM.