Scania has done some testing with COE vs conventional. COE proved better because the air has to change direction fewer times. BUT big but if you are going over 83-85km/h you will start pushing an air bag in front of you meaning the fuel consumption skyrockets. But mostly it’s up to the driver, lifting of the gas at least 800m before the turn, try to roll just as much as possible and remember to turn the truck of when stopped. You usually don’t need to idle after you stopped because the time you used to get there from the freeway is enough to cool it down.
The r580 I been driving the last 2 weeks shows 7,01mpg after 3000miles, been in a hurry for about 1000 of those, the other is just economical driving as possible + a lot of hills . That’s with the full 25m combination and always over 40t total.