Does anyone know of a dealer that has figured out how to install Sirius in a 2004 645. BMW decided not to "prewire" some 2004 cars with Sat prep, even cars where Sat was ordered. They now say Sat can not be installed. I can't believe that a simple $2-5 part is the problem. Any suggestions

You might try contacting Alpine Electronics. I believe they, or the parent company Harmon, are the OEM for the audio systems for BMW.

does your factory radio have changer controls??