Had my Acadia for 1 week when I heard a loud noise/vibration when I got up to about 4000 RPMs. I immediately drove to the dealership for them to hear it. They did not have an answer and of course I had to bring it back for service. The noise would only happen when the AC was on, so we narrowed the problem down to the AC. Long story short, after 2 days in the shop they realized that there was a bolt missing that held the AC to the frame. They fixed the problem, but I must say it was somewhat disappointing for that to happen on a new vehicle. With all that being said, I still love the car.