My mother in law's 2001 3.0 has had a few issues in 77K miles, but nothing out of the ordinary or terribly expensive. She bought it new in December, 2001. The biggest difference seems to be whether or not the PO followed 'old school' maintenance schedules for fluids, etc. If not, they're on the BMW-will-sell-you-a-new-transmission plan. Well maintained, these things can go on for a long time.

Seems to me that you're trading one ten year old car for another. Not much of a difference, really. The same issues would likely crop up on either car. I'd do it if your chief complaint- ride quality- is more to your liking on the X5.

__________________