This info is speculative.
I believe that sending the Audio to the BMW Mount in the BMW Nuvi (OEM 3760) is achieve by OEM.XML combined with the BMW Logo.bin
The OEM.XML is deleated from the Nuvi Drive after it is installed.The contents of the file are copied to a region in flash. (on the 13xx it is region 101, we don't know what it is on the BMW 3760). The OEM.XML is only parsed (activated) if the correct logo.bin is installed as there is a special number inside the Logo.bin eg D1340-65 for a china nuvi 13xx.