Pushing 255K on my 01 X5 3.0i, still running original brake and trans fluid, both trans and engine are still smooth as butter. Biggest expense so far was the airsuspension rear I should have done myself but didn't about $900, and the transfer case and front drive line/shaft that failed which set me back about $2600 total original BMW transfer case was ordered new for about $1800, plus $150 for an aftermarket drive shaft and about $600 in labor. About to do sub frame bushings and rear struts since I have the squeak waking up the neighborhoods I drive through. Any question on the original brake fluid read my more detailed post here I uploaded a long time ago. X5s today are nowhere near as good as the first generation. BMW I believe over built, over engineered the damn thing since they weren't sure how it would hold up. Once they figured out what they could get away with they shifted to lower quality parts and components in later models. Feel free to ask any questions