I have the same problem with the back end of the car jumping sideways. Living in Wisconsin during the winter, this car is very difficult to drive on snow / ice covered roads. When you go from snow or ice covered section of the road to a section where the car can get traction, the back end of the car jumps sideways. When you go back onto the snow / ice covered section again - it again jumps. Even driving 25 mph through the neighorhood streets in the winter, with the trees shadowing part of the road from the sun, the car will jump everytime the road condition changes. With the road being icy, I have to slow down considerable compared to past cars I have driven.
I do not know what the solution is - but I am trying to get it resolved.
Maybe I need 4 wheel alignment?
Anyone else have this problem and resolve it?