Although webasto is a good company for sunroofs i will not recommend you putting one in the beemer, just don't think it would suit it but that's just my opinion.
My sister just put in a Webasto Sunroof on her Jeep, it set her back 10 gees but i can really say it suits her Jeep but picturing it in a beemer, i dunno, it seems odd without the factory glass sunroof but its your choice at the end of the day