i kinda specialise in tuning pd150 and can get these to get anywhere between 50-68mpg.
I like to test with £10 and £20 worth of fuel on my own pd150,
last £20 of fuel test I carried out which included too and from work and out n about normally - I got 190 miles with my latest development tune works out to be 58~ mpg over the £20 of diesel at £1.34 a litre
This is whilst being remapped for smoke free power, Egr deleted and decated.
Believe it or not I was getting 66mpg over 24miles before the decat was fitted when driving sensible, still have the picture to proof it.