Bentley is OK, not perfect but has helped me for specific questions (I've redone the front & rear suspension, some interior seat & trim work). It's an adequate base, which I've supplemented with Xoutpost (of qualified content), Bentley YouTube and careful gleaning of web info (not all the glitters is gold).

For those with non-North American cars (like mine), the understandable lack of information about the (diesel) M57 engine is unfortunate - but there are some good German & French language forums which helped me.

If you are an avid DIY person, buy it. If you only do oil & filter changes, you'll make less frequent use of a thick book.

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2002 Euro X5 (E53) 3.0 diesel (M57)
5 speed manual with UUC short shifter.
Pre-xDrive NV125 transfer case (chain & gears).
Factory Xenon headlights, Spyder LED tail lights
Updated vortex crankcase breather.
Motorsport dead pedal, factory fire extinguisher, factory first aid kit, factory F&R mud flaps, factory PDC

Bilstein B6 shocks F&R
Redline oil has replaced "lifetime" fluids (F&R diff, manual transmission, transfer case and P/S).
Dimple magnetic drain plugs in all compartments.