Check the condition of door and trunk rubber seals. A rubber seal surrounds the outline of each door. If the rubber is hard, cracked or missing water and wind/air will enter.
Many 'Fest members use a product to treat and protect the rubber keeping the seals soft playable and lush.
Do a search on door or trunk seals.
2008 328xi E90|N51|monaco blue|premium|sports|cold weather|logic 7|ipod|BMW Assist|xenon|sunshade|HD radio