2017 xts, rear suspension air bags fail while driving, stoped and even parked. while driving at highway speeds or just parked rear end will drop unexpectedly. the rear end will start to bounce with just the slightest uneven road. this cause the driver to have to fight to stay in control of car and slow down very fast. with traffic behind it can cause someone to hit you from rear. car has been to dealer several times and cadillac say everything is normal. however after leaving dealer it continues to happen. cadillac has know about this for many years and ignores the problem on the xts. the rear end will drop to a level the you can not even touch the top of the tire or even the middle. almost touching the ground at rear. first time was april 2019 right after warranty was out. the said i needed shocks 1500.00 did not do anything but drain my wallet. cadillac needs to own up to the problem and fix it.