I'd thought I'd come back to this thread, on my Audi (2006 3door sline TDI 140) I'm only getting 475ish miles out of a full tank, I've done three full tank full's now and calculated (from brim to brim calculations) I get 42mpg (also what the computer says). I've ignored my first full tank full as I was flooring it for a while, but now I've settled into my work commuter.
I don't really drive fast, hardly ever more than 80mph but keep up with traffic so cruise at 70-75mph. My commute is mainly motorway.
I really was expecting much better than this, I got a true 48-50mpg on my 2001 Golf TDI 130pd.
I have checked the basics, tyre pressures, air filter is brand new. It's also going into the garage on thurs, so want them to check it out. Should I specifically mention the fuel temperature sensor? They will probably say it's all ok, but you all of you are getting far more than me and I do know how to drive economically.