Our Cruze has 120K miles on it. It has been a wonderful car in many ways but it has unfortunately had a lot of body work (deer, tree falling on it etc). At this point the front struts have been replaced twice in less than a year... Once with mystery parts from a body shop as part of an insurance repair and now recently by a Chevrolet dealer. The rear shocks were replaces less than a year ago and frankly, that swap out didn't seem to change anything. The dealer who just did the front struts claims to have carefully inspected the entirety of the front suspension and says everything looked ok. We also replaced the strut mounts/bearings just in case and an alignment was done so it was a very expensive repair. It hasn't appreciably improved our situation.
The performance issue is kind of strange. On good smooth roads the ride is of course perfectly fine. There isn't a single thing that squeaks or rattles anywhere in the car which is amazing to me considering its age and hard life. Over normal crummy roads (lumpy patched asphalt, non crumbling dips and small lumps) the ride is not terrible. It's not supple or great but it also isn't bouncy, loud or upsetting to the cars trajectory. Parking lot speed bumps taken at the intended low speeds are fine. But over slightly sharper bumps (poorly done bridge joints, any seam between two pieces of pavement where there is more than a tiny vertical change in level, some sharper dips etc, some deeper manhole covers) the car SLAMS through the bumps with a very loud and disturbing whack that seems entirely out of proportion to the bump. Sometimes there can be 3 or 4 little bumps in a 1/2 mile section and 3 of them are normal jiggly car suspension doing its job bumps and one (which looks only a tiny bit worse) feels like you drove over a curb at 25 MPH. Not sure how to describe it any more accurately. I can tell you that there is no rattling worn out taxi cab type sounds going over speed bumps etc. I had a Malibu with sway bar issues and that made a distinctive sound which this car has never had.
I remember reading some snarky phrase that said something like... if you think your suspension problem is in the front, it's probably in the rear and if you are sure your problem is in the front, it's almost certainly in the rear..... Assuming that the really great dealer who has seen the car many times hasn't missed something in regular inspections of the front and given that the strut replacing dealer swears they road tested and inspected carefully and couldn't come up with anything other than struts to replace... Is it possible something is terribly wrong with the Z-Link or some other rear component and what would we even look for back there?