I've had my 2013 LS460 F-sport AWD for almost a year. Bought it with 19K miles on it, currently has 40K miles. Problems started when I took it to a non-lexus service shop to have new tires put on it. I went with the pirelli cinturado (sp?). After that, the car would shake uncontrollably anywhere from 40 to 70 mph and I felt every bump in the road. Had them rebalanced 4 times and eventually decided that I had just purchased bad tires. Replaced them with the OEM brand. Still shaking. Had them balanced 3 times, and then road forced balanced. The shaking subsided. However, the car still rides awful. I mean, every bump, every indention in the pavement, I feel it. I've heard the front end make noises going over speed bumps. On the interstate, it feels like the front suspension and tires are bouncing on the pavement like you would see/feel in a very old worn out suspension, causing the entire car to shake. It's an up and down rapid bouncing/shaking, not the swaying "boaty" feel. The car went from one of the smoothest riding cars I've ever had, to one of the worst. Been to Lexus three times, they say it's fine. Also, there is no difference from normal mode to comfort, sport, sport+ at all. I'm at my wits end with it, and really don't want to get rid of the car when I know there is something wrong that can be fixed. Something happened to the suspension while in that tire shop.
Any ideas of what could go wrong? It's hard to fathom the shock/struts going bad almost over night at 40K miles.