Yes the HHR was done under Lutz so it did see some improvement.
GM did get it about interiors but they lacked money to really finish a car. Scott Settlmire of the F body program said they always had just enough money to do the suspension and engine but always ran short with the interior. Today that is no longer a problem on each new model and the old ones are replaced.
GM back then could not even afford to market the HHR SS. That is why you never heard of them and they only has a little flyer insert at the dealer.
Things at GM were bad much longer than many realize. That is what is so exciting today as they for once in a long time are really finishing cars. The new Malibu will shock many how well it will be refined for the segment.