AFAIK, any 6 series 84 (or 85 or 83, I have no idea) or newer has a door lock heater. When the driver's door is locked, and you pull up on the handle from outside, it should engage a small heater element in the door lock. Unless this has broken or has been disconnected (sometimes it stays on, which drains the battery so some owner's disconnect the heater), it should heat the lock until it is possible to turn it. hope this helps! -aaron Forgot to mention I have a 1987 635CSi.