Quoted $600AU today to replace 1 C.V. Boot drivers side. C.V. boots are the bellows shaped rubber covering that enclose the C.V. Joints and keeps the assembly away from dirt and water. There are 8 separate C.V. Boots on an X5 that extra warranty does not cover, as they're wear and tear items. If you don't replace them quickly, serious problems will develop! Now, imagine if you had to replace several or more of these boots in a single service? That's why BMW X5s cost $$$ to keep running. It is not the parts which are expensive, it is the work needed to remove and reinstall the wheel assembly that costs. They will need to be replaced every 6-8 years. Be prepared.