Glad to see that the valve stem seals have already been done. That was a big expense on mine, which the extended warranty thankfully took care of.

As far as transmission goes, you may experience a "clunk" when downshifting from 2nd to 1st gear, especially when it's cold. This is pretty normal and can be resolved with a transmission software update. When I had the update applied to mine, it changed the shift pattern so that the clunk was eliminated and it was a lot snappier off the line. The downside is that I lost 2mpg (18mpg average to 16mpg average).

The indy shops I worked with recommended draining and refilling the transmission fluid before 80k miles. Note that they recommend not flushing the transmission for fear of knocking gunk loose which could clog the system and cause problems. You'll also have a mechatronic sleeve seal to replace, which is a little expensive to do but good preventative maintenance.

If available, I'd consider an extended warranty. Mine cost $5k but covered over $8k in repairs before I traded it in. And since I traded in the X with some time left on the warranty clock, I should be getting a partial refund.

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2006 X5 4.4i
Sport package, summer package, cold weather package, DSP + Nav
Bought 2/14 with 73k miles