Hello friends, I am quite new in this forum. The reason I joined is my recently purchased 2013 GMC Yukon. The car is awesome and I am very happy. However, there are few minor issues I would like to discuss. The drive of this Yukon is very smooth with nice acceleration and power behind the wheels. The car when running runs smooth and quiet. However, when on idle (e.g., when I stop behind the red light or in the parking mood), the car starts to rattle. The rpm looks low to me, going down to 500 rpm! This morning I showed the Yukon to the GM dealer mechanics and they said that the truck is smooth and it is normal. Doesn't look like normal to me. I asked them if they could tune the engine to stay on higher rpm when on idle, they said this is not possible as all these are controlled by the computer... So, they did nothing about this. This is not a deal breaker for me, but I really want to solve this issue. Any info or help is greatly appreciated.