[jandref321]

All BMWs are going to have maintenance requirements from 75k-100k miles usually including all of the cooling system, suspension bushings, fuel pump, oil pan gasket, and valve cover gaskets. You will also have your normal maintenance of brakes, oil, spark plugs, etc.

The S63 has fewer issues than the N63 but looking for reliability in an M car on forums doesn't speak for normal use. M cars usually run an edge between performance and reliability in the first place. All their parts are going to be more expensive than normal parts on the same chassis. Additionally, most of the people you find on the forums are usually modding their cars to the point where reliability is non-existent.

You will have higher cost of maintenance in the X5M or any X5 because of the Xdrive design. A oil pan gasket replacement on a 2wd M3 will be cheaper than an oil pan gasket replacement on a X5 35i because the front axle runs through the oil pan. This is the same for the X5M, which has two oil pan parts: a lower and an upper. The lower is easily replaced but the upper requires the hubs, axles, differential, drive shaft etc to be removed before replacing the gasket. Cost difference? Indy shop might charge $400-600 to drop the subframe and steering rack to replace a 2wd oil pan gasket while they would charge $1600 to do an awd oil pan gasket.

Here are the things that have been done since I purchased my car (most under warranty:
59k miles - Exhaust Vanos Solenoid Bank 1
59k miles - High Pressure Fuel Pump Bank 1
59k miles - Fuel Injectors replaced cyl 1-4, 7
63k miles - Fuel Injector replaced cyl 8
63k miles - Turbo coolant hoses replaced
65k miles - Filtered Air Ducts replaced
65k miles - Charge Pipe hoses replaced
67k miles - Ignition Coils replaced
67k miles - Spark Plugs replaced
68k miles - Oil Pan Gaskets replaced, upper and lower
68k miles - Fuel Injector replaced, cyl 8
72k miles - Rear Air Springs replaced