For what it is worth.....sounds like too much money for either of these...and IMHO I have a 2006 3.0, and I find that it has more than adequate power, (unless you intend to pull a big trailer) and I think the 6's are far cheaper to maintain and a lot less trouble.
There are a lot of X5 for sale, find one that doesn't already look like a rat.
Also, save yourself a lot of fees and find one privately, look for one that has been owned privately for a few years...(not a shoddy dealer selling out of his house)
I think a "nice" 02 should be around $10,000

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