I purchased a 1992 735il last winter which has been a great automobile. A problem has come up with the auto and I would appreciate any suggestions. The car, after sitting out in the sun has developed a bad smell upon starting up. A urine like smell is noticeable when the fan starts up. The smell goes away as the air conditioning picks up, however it can be quite strong at first. I am not into air fresheners, but there must be something out there to clean out the system---so to speak. Any ideas??