I wouldn't be scared of an ex-rental 5 at all. $6k will buy the whole powertrain and have it installed, plus replace most of either the suspension, interior, or body if you feel like it. AND, that's $6k NOW vs. the very small potential for spending a portion of the $6k at some non-specific future time.
I haven't sat in nor driven an '08, but it's possible they're nicer in some way I'd care about. If we had an A/T, I'd really like an '08, but I surely wouldn't trade in our '06 (i.e. pay $6-9k) just for that. I agree that I'd absolutely insist that the ATF and filter be changed before I took delivery, and of course maintenance records would be very nice. Still, if it didn't have them, my impression is that a private owner who just has a short- or medium-term lease (i.e. turns the car over every 15-25k miles) is actually much less likely to do proper maintenance or any maintenance at all than a rental shop. Not to say all leasers are poor maintainers, nor that all rental shops are good ones, but rental shops are usually regular about that.
Let us know what you end up doing!
