I'm a relatively new Model S owner and have been unable to adjust the seat/headrest to my liking. It appears that the headrest is non adjustable and is positioned about 1.75 inches in front of the seat back. When I adjust the seat to my liking my head just touches the headrest. So each bump in the road bounces my head forward and backwards. I have found the only way to prevent the head bounce is for me to sit leaning forward pulling my upper back off the "bucket" seat negating some of the benefits of the seat. Has anyone else had this problem? Is there an aftermarket headrest?