One problem related to tail light has been reported for the 2006 BMW 5 Series. The most recently reported issues are listed below.
The taillights of Bmws (made in about the last three years), some Lexus (starting about two years ago) and some cadillacs (starting about a year ago) use leds that are modulated on and off. These can become a distraction at night when moving one's eyes quickly from side to side. It can give the illusion that there are more cars on the highway than there are.