my motor mounts and transmission mounts were replaced at about 30k under warranty although I had not specifically requested that be done. However, after they were replaced, at a stoplight the car was amazingly smooth, no vibration. So despite what they say about a inline 6 being inherently smooth, the motor mounts have a huge impact on cabin smoothness since no tuneup was done.

Recently, the car now has 63k and the car, of course, is not as smooth as when the motor mounts were changed but I recently notice that when starting the car, the last moment before the car settles into an idle there seems to feel a momentary rotational shift in the engine or out of sync feeling. After that, it is normal. Anybody know what might be the cause of that?