The key to buying a used X5, and for that matter any used vehicle, is to find one that has 50-60 thousand miles, one or two owners, a complete maintenance and repair history and passes a pre purchase inspection with flying colors. I would not recommend buying any used vehicle that is ten plus years old unless you can DiY.

Since there are not that many out there that are lesser risk vehicles I suggest you are also open to a V8 that is a great find. Mileage won't be all that different depending on how it is driven. Regardless of what you find there is enough risk that one should budget for repairs.

Welcome and good luck!

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas