yeah it makes no difference on a 9 hr trip, but it does using the ER on a 15 hr jolly.
I guess if everyone of our ER flts to the and from NA were to go CI 20 and save 200 to 300 kg's it would add up( currently 6 flts a day x 300 kg's = 1800kg's or 2,300 lts or about $2,500 USD ). So worth doing, and it can mean extra money for the drivers too ( through our Hourly Duty Pay system, even better if you are on overtime )
So it can be a win win for all
Having said all that above it does make you laugh when the company expect you to save every kg of fuel and then the Engineers run the APU for 6 hours on an overnight stop in TPE.
( uses around 1,200 kgs or more )