80K km is pretty low miles. If the car checks out and has good maint records, you should be in good shape. Of course as others have said, BMW's in general and X5's specifically have some inherent issues where some preventative maint. may be called for. Similar to what you would find in a E38 7 series or E39 5 series with the V8.

I have 106K miles on mine. It was a former CPO car with all BMW factory service and repair history. Common items that have failed past 75K miles on mine included:
- water pump and expansion tank
- alternator
- CV boot
- valve cover gaskets
- oil pan gasket

That's pretty much it. So like any BMW they will require some care and feeding, but if you want a sporting luxury SUV there is no better alternative than the 4.6is or 4.8is, IMHO. Very fun to drive and top notch features and appointments on the "is" models, not to mention you don't see them around all the time. They sold less than 2K in NA for the entire 4.6is model run. I figure the 2003 is the better year to get for the 4.6is because it is the last year of the E53 before the mid cycle update, so generally BMW had more time to work out the kinks. As repoman says, these are not Lexus-like in terms of reliability. But by the same token are not lexus like in terms of driving pleasure, which is a very good thing!!

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2003 4.6is - SOLD
2003 M5 Imola
2008 Mini Cooper S
2011 Mazda CX9