So we've had this Santa Fe for about 2 years.. The rear has always been very rough - even compared to our previous F150. Now our roads aren't perfect, but where our Subaru just absorbs some rather normal road bumps, the Santa Fe will "bang". The dealership is useless, every time they check they say nothing is wrong, and they hear this year/model has a rough ride. Load doesn't seem to matter?

Unfortunately we don't know anyone with an XL, but we do know a few people with a similar year Sport which does not have this issue.

Is it a known things with the 2017 XL?

 

Not sure just what the "bang" is at this time.
If the rear is "bottoming out" , going against the limits , that would be bottoming out.
There are some general things that we need to know.
On the driver's side door, latch area, should be a label stating the correct tire pressure for your particular vehicle. Front and rear tire pressures could be different, not all are the same. Has anyone checked this? Don't rely on the dealership to have done this. Let's check this for starters, OK.

 

Thanks for the reply. Inside the door it says 33 PSI. All tires were at 38, so I did drop them to 33 and that has smoothed out the ride considerably on smooth roads.

I have a hitch mounted bike rack. I can basically bounce fairly lightly on the tounge and get the rear end to bottom out tho, which I'm guess where the bang is from larger bumps. My feeling is the rear end is just too soft maybe?

 

Did you get a chance to look under the rear at the struts ? What you are looking for is any signs of wetness where the strut compresses. If wet , they need to be replaced.

Shocks are supposed to dampen any bumps. If the are worn internally, they don't provide much smoothing out as they should.
Check around and see if they have something like heavy duty struts for your vehicle. Don't forget the stiffer the strut, the harsher the ride.