Hey Mate,

I have owned two X5s, a 4.4 and 4.6, both 2003 models. The 4.4 has 94K miles on it which is equivalent to the 150K kilometers you mention. Here in the US you can find a clean 4.4 with 75K miles for 13,000 to $20,000 US$ depending on the year. Not sure what they go for down under. I would definetly go for the 4.4, fuel economy will be similar betwixt that the 3.0 but you will have more towing capability with V8. Try to find one with a towing package already on it cuz you will spend a few $ to install one on it.

Peruse the forums for the usual suspect items that need replacing. Expect to start replacing things like CV joints and other front end components, cooling system items. I have had good luck with the 4.4 so far (knock on wood) but the 4.6 has been a lot more costly. For safety, and other issues you mention the X5 is a tank. Good luck.