This is the third time I've gone to the dealership this time and finally they are agreeing with me that the noise I'm hearing is a rear-end whine. Now the only problem is they said if it was them they wouldn't worry about it. They'd just ignore it. So I've been from It's a tire noise, to its an exhaust drone (whatever the hell that is) to finally rear end noise. They did tell me they were going to call the MB dealer and see what they say about it, and they were going to check for a TSB on it.