I had the same ride quality issues, then I realized that the demo car I took out had Michelen tires and was a smooth ride, when I took delivery of the car and drove home from the dealer I noticed that the ride was harsher so I took a look and now noticed I had Bridgestone's. I went back to the dealer and after a couple of test drives with tech I was able to swap out for Michelens and it made a difference. I hope this helps.
P.S. I beleive the article in CR pointed out the differnce in tires when they did a review of the ES or GS.
