I'm looking at a 2017 Volvo VAH64600, D13, I shift transmission, Wallymo head rack and trailer, 460k miles. I still have to do all my inspections...
Any Volvo car hauler guys out there. I ran into a guy saying he was getting better than 6.
I'm basically the same set up as you but your mileage is much better. I need to do some digging. BTW what oil temps are you running fully...
I'm curious what everybody is getting with their set up. Mine: 2014 Pete, 9 car cotrell trailer ISX 15 13 spd. I average just under 4mpg otr.