My 2017 Acadia Denali has a defect/problem in the moon roof or moon roof shade which causes a chatter or vibration noise when driving down the road. This is from both moon roofs. They rattle whenever you hit the slightest bump. It is annoying and loud. Since you have two moon roofs in the vehicle the noise is multiplied. The noise can almost sound like a very loud humming on concrete sectioned or very bumpy roads. Once you start hearing it the effect is magnified and not what you expect from a new $50K vehicle. My 2008 Highlander makes less noise going down the road. When we test drove the car the moon roofs were open and so we heard no vibration. So far the only way we have found to stop the noise is to keep the shades open ALL the time. This is unacceptable in a new vehicle. The chatter is much worse on older roads or concrete slab roads. The dealership has verified the noise on numerous occasions, but said, “We have done everything we can.” When I asked them if it should be making this noise they said, “No.” The dealership has replaced the front moon roof shade once already. They tightened both as much as they could, but they still rattles and vibrates. As time goes on they loosen back up and the vibration gets worse and loader. This is not what I expect from a vehicle that is less than a year old and it will not get any better. The mechanic at the dealership has stated,” it is a design flaw.” I believe this will NEVER by fixed or addressed by GMC, because it would cost them too much to fix it right.