I don't think diesels ever truly stop running in/loosening- my last 4 or 5 cars have all seemingly got more economical throughout their time with me (generally 50-80k miles between changes). My A5 3.0tdi had 78k when I changed it for the T6. When it was new, range would show approx 540 miles when brimmed- when I sold it, it was around 700 miles projected range.
Don't think I'll see this on the T6 somehow although to be fair, I'm getting around 530/550 miles between fill ups (takes 60 litres to brim from 10 miles left showing on range)