I only purchased this 5 weeks ago and it is winter. So I can't tell you a lot. It has power for 6.0L. I purchased the 2500 instead of 1500, because I just bought a 37' 5th wheel, which I will not be able to for 3 months or that warm weather arrives. So the gas mileage is only 12.3 right now. The ride is pretty sift. Lacks inside floor storage need to add plastic under rear seat storage. Don't like the fake ram air on hood.
I bought the truck brand new from a local Chevy dealer. The truck is only 1.5 years old and it has 37,000 miles on it. So far, the only time I took it to the shop was the to get the free oil changes and tire rotations. The fuel mileage I get: average highway traveling 65 mph is 22 mpg. Average highway traveling 75 to 80 mph is 18.5 mpg. I live in the southwestern part of PA so, traveling through the mountains I average 15 mpg.
It is the most comfortable truck I've ever driven. I drove it to Colorado 27 hrs straight through. My back and legs felt fine at the end of the trip.
As far as the power it has; I occasionally pull an 8,000 pound travel trailer and at times I forget is behind the truck. One of the features I absolutely love wether I'm towing or going down the mountain is the engine brake. You cannot go wrong with this truck. At this point, I only have praise for this truck. After 75,000 I will update this post. The only bad thing and I'm sure I'm not the only person who feels this way, THE DEF FlUID IS A PAIN IN THE ASS!!!!!!!!!!!!!