Gotta love the BMW 3.0 Twin Power diesel 309 BHP 465 lbft, goes like a very goey thing and has done this or there abouts on every mid/long trip I've done in the last month (about 2.5-3k)...
Last time I filled up I had a predicted range of over 700 miles.
I do like the 640d quite a lot, the build quality may have been a little below what I'd expect but its comfy, quick, has an immense sound system and it looks great. Got parking it sorted in the flat car park now, which involves reversing in to the garage, and I'm still scared of scraping the wheels or the nose (because its that bloody long) but with the surround view it makes life much easier.