Got a chance to drive a G6 hard top convertible over the weekend as my rental - have to say I was surprised by how quiet the cabin was compared to the SLK, both top-up and top-down. The interior material and the trunk were terrible - the trunk, in particular, almost has zero space if you were to let the top down. Worse yet - there was no "floor" in the trunk; there's a big spare tire in the middle, and your belongings just sit unbalanced on it. But.. the car is extremely quiet. Passengers who wheren't car-savvy had no idea it was a convertible. I also drove it on the freeway with top-down -- much quieter/significantly less turbuent than the SLK. The body also feels less prone to flex than the SLK - no creaky noise over bumps, etc. (This car also has 12k miles on it already, and doesn't appear to be well-maintained by the rental agency.) What a surprise.. Pontiac designers must have done something right with noise insulation/aerodynamics.