I had it back to the dealer yesterday. They drove it and decided to balance the tires, now I have a new different vibration. I will get them balanced again at my tire shop. They put a different tech on it, he suggested it might be an exhaust drone. He had it awhile and then they asked me to go drive it. It appears to be gone for the time, but now I have a little tire hop at 70 mph. I asked them what they found. They used stick on wheel weights, stuck them to the exhaust pipe between the catalytic converter and the NOX filter, and put a hose clamp around them to keep them there. For future reference, I guess you need to include getting your muffler bearing balanced in your regular maintenance schedule.