Signature 600 series Cummins ?

I have to disagree. Drove an 01 eagle with the N14 in it and was pretty impressed with the brake on it with 80k. Pretty much as good as the C15 in my truck. Wasn't all that impressed with the ISX though but it was tired and lived a rough life so probably not a good comparison.

 

Just speaking for myself, can't speak for anyone else but I have one I drive daily, it gets 5 mpg all day long grossing 90K, in nothing but hills and stop & go, under permit here in my state. When I hook to a different trailer and lighten up and go on the road a little I have seen 6.2 mpg...
It pulls like a locomotive and haven't had a bit of trouble that I couldn't get out of with it yet. The engine brake is by far the strongest one on the market to date, about 40% stronger than the competitors...I use it quite frequently daily on 10-12% grades here in my area.
Downside is the driveability factor. They are contankerous to drive compared to a Cat. You have to think about every single move your foot makes along with your right arm, and 50 rpm's means the difference of grabbing a gear or not with an ISX. Not very driver friendly. Just my .02.

 

I had an 01 w900 with signature 600 got 6 mpg grossing 80000 running nortwest pulling a reefer, when I pulled a grain wagon it jumped to 7+ mpg went through 3 turbos in. 1.5m rebilt it at1.4m liners were like mirrors wore out. Still pulled great. Oh 1 injector was leaking water and was Rusty.

 

holly thread revival Bat-Man this was started in 2008 and revived again in 2015