I have an 2007.5, 6.7 Commins w/6 speed auto. I use it to mainly to pull my boat. I live in the NW and do mainly mixed driving. It has only 26K miles on it as its is not my primary vehical. This is a towing machine. At times I almost forget I have 8,000 lbs. behind me. I know some 3/4 tons can tow that. My last truck was a gas 3/4 ton and was rated for that much. It was working way to hard. Gas milage is great and will get better with age. In mixed driving about 13. Get it on the Freeway about 20 mpg's @ 65 running on 35's.
Bought truck with 20k on it. 2 years later have 160,000. Change oil regularly. 1 trans flush. Only been in shop twice for a total of 200 dollars. I drive all over the state of Texas to job sites in the middle of nowhere spend all day in 4wd at job sites and then get back on road for another long trip. I have had them all. Strokes, Maxes, all of them and the 5.9 is by far the best ever. Have the auto trans and have had absolutely no problems with it. If you are looking for a diesel HD don't even think twice about a Dodge Cummins. Just buy it. They will solve the emission problems. The Cummins is the simplest design and the toughest and the most reliable, etc, etc..
My truck has experienced the "Death Wobble" at least a dozen times. The dealer will not fix the problem even though there is a technical service bulletin# 22-005-06. I had the problem fixed by a non dealer mechanic but it will cost $3000 to have the front steering and axle rebuilt. Parts inclued: 2009 Steering Upgrade Kit $400 plus labor, Ball Joints $600 plus labor, Steering Stabilizer $200 plus labor, new needle bearing in the steering box $200 plus labor, and a 4 wheel steering alignment $100. Also, make sure you have good E rated tires with the correct air pressure for the tire size. The problem is more common on 4x4 trucks with a diesel engine due to the weight of the engine.
The 6.7L diesel has major problems. The engine clogs. I have had the truck contantly into the shop. Dodge does not have parts available and does not seem to have a fix designed. The engine parts need to be replaced or cleaned constantly. The fuel economy and power drop with each trip to the dealer. I seriously recommend NOT buying a Dodge with this engine. I paln to try to get different truck via the lemon laws in our state. The truck has been in the shop for the same problem over and over and is going in again soon.
I bought the new Dodge 6.7 when it came out, What a mistake! I have had nothing but trouble with the emmisions have had the truck in the shop 5 times for the PDF filter stopping up. I don't think that the regenaration system is working and have brought that to dodges attention but they insist it is working. Engine light has been on 90% of the time I have owned this truck. Bring back the 5.9 please. My brother has a 2007 with the 5.9 and has had NO PROBLEMS. The 6.7 has been a sore in my side since aI bought it the best thiong on the engine of this truck is the jake brake system and the 6 speed transmission. Take that and bring back the 5.9 and you will have something. 6.7 IS A LEMON!