I absolutely love my recently acquired 2008 630i, which feels much more lithe and less nose-heavy than the 635d I ran a few years back. However, I did get a print out of the warranty claims on it (after I'd got it) which was a bit of an eye opener! I also needed a new fuel pump 4 weeks after it arrived which fortunately was covered under warranty. I don't know whether you're buying new or used but I'd suggest a warranty would be a very good idea - these are complex cars.