I test drove one for about 30 minutes. It had about 200 miles on the clock. Rode pretty smooth, didn't have any payload to test that part but I liked it. I did some highway driving and got it to show me 25.5 mpg at 65-70mph. I was driving with my foot so it might have done better with the cruise on. I took it on city streets, dirt roads, pothole plagued dirt roads, and of course the highway. I had a trailer with about 4000lbs of metal and trailer combined weight I would have loved to test it with but I didn't think they would appreciate that since I was just looking anyway. I felt like it would have handled that load with ease. The 91 Chevy K1500 that I was using to pull that trailer would have a tough time doing it as easy as that baby Duramax I bet.