Water ingress can do anything so cleaning all the drains would be the first port of call (also kinked drain hoses on the A pillars if the vehicle has sunroof). Blower final stage resistor and it's wiring is probably the only thing I would do something preventative regarding electrics. The pins on the FSR connector can get loose over time. You can remove the connector and use some contact cleaner and contact paste on the pins.

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E39 530dA -02 M-Sport Messing metallic
E53 X5 3.0dA -06 Sport Stratus grey
E70 X5 40d -12 M-Sport Space grey