I have a 2007 Tacoma with an automatic transmission (double cab, long bed). Since new, it has made a growling sound from the drive train when driving at low RPM. It seems to do it worse when the car is cold. I thought maybe it was something that might go away as parts wore in, but 3,000 miles later it's still doing it. Has anyone had the same experience, or know what this might be? I'm just wondering if it's something that they all do? I haven't asked the dealer's opinion on it yet.