Originally Posted by
n plus one
My fuel economy didn't settle until around 40k.
I also had one incident where the truck got much thirstier after LR serviced it - to the extent that the EGR started to soot up badly. Got the truck serviced again (at a different dealer) on the same trip (it was a 14k run) and economy returned to trend and EGR came back to life - so keep in mind it might be your tune that's affecting things.
A (reportedly) reliable strategy for improving economy is to drive to your EGTs - I haven't tried this yet, but I'd certainly advise monitoring EGTs to those who tow heavy loads - rumour is that you can cook the turbo on the standard tune if you try.