I see your point. I haven't done this exact comparison, but can make a guess as to what is happening: At 60 MPH, the 2.0 should downshift into 4th gear. If it chose 3rd gear, it would be a very short time before needing to up-shift (about 400 RPM) and it would seem to gear hunt. At 60 MPH the 3.6 likely downshifts to 3rd, and has about 1100 RPM before the 4th gear up-shift. A 2.0 in 4th gear has less torque at the axle than a 3.6 in 3rd gear, making the 3.6 the winner.Since I started this thread, I'd thought I'd ensure clarity with what I think would be most important for those using a Rubicon as a daily driver and are concerned about safety.
It's not passing someone at 115mph, it's not zero to 60, .......it's driving on the highway at around 60 & needing decent acceleration/tourqe to pass a tractor trailer who could change your life with a 4 degree steering wheel directional change. I dont care if it's the transmission or engine or combination of both. I just dont want the vehicle to hesitate from 60 (or 55) to 70mph. I experienced this on a consistent basis with the 2.0. I will continue testing both, as well as the 3.0 eco diesel as my purchase is not till year end & may well be a 2021 model
At the end of the day the 3.6 has more horsepower, and with the stock gearing above 60 MPH it looks to have slightly more average road force (at WOT). I would expect the diesel to be worse in this comparison.
The graph below shows the Rubicon 8-speed 2.0 (solid) & 3.6 (dashed). The black line is at 60 MPH.