Here is the file. The speckles are visible in the metallic layer of the carpaint (see MtlSelect render element). I narrowed it down to one light in the scene. Increasing the subdivs of the metallic layer helps a bit, but I need that scene completely noise-free.
EDIT: wtf, file size limit for zip is 97kb? Come on… Please send a pm and I will mail the file to you. It is about 600 kilobytes
Regards and thanks for the help
Oliver