I purchased 2016 XTS FWD 10000 miles as a CPO. I knew it had a vibration when I test drove it, expected it to be covered under warranty. The vibration starts to be evident around 50 mph, vibrates at the same rate no matter the speed and continues to over the speed limit. Vibration can be felt in the floor, seat and steering wheel. Dealer has checked wheels for trueness, still vibrates, road force balanced the tires, still vibrates, four new tires, still vibrates. Run diagnostics and used a pico meter, still vibrates. Dealer says they all do this and they can't fix it. GM sold 22,000 of these, I can't believe they all do this. Looking for some feedback from anyone with a similar car.