Cheers for the comments guys.
About my driving style, my drive to work has been the yardstick as I have always driven in a consistent way to work. I feel the economy and performance of the diesel has improved with the miles, so yes Munro, I do beleive the engine is "loosening up" all the time.
I would say that when i'm driving home from footie or the gym at night when the roads are quiet and i'm not in a rush, a steady mid 50's mph delivers nearly 60MPG. Then sometimes when the roads are quiet at night, I might only get 45MPG
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On a funnier note, I met my pal with the old BMW today, he had broken down! Hilarious!