There were problems reported on 2004 models that the drain tube for the panorama roof was getting kinked during assembly causing it to leak. Might get yours checked or replaced. There is a service bulletin out about this.

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'05 X3 3.0i Alpine White/Gray Leather/Alum. Trim
Sport/Steptronic/Servotronic/Panoramic
Prem. Sound/Staggered 18" Style 114 Y-Spokes