NHTSA Complaint #11693716 — 2024 KIA EV9

When driving between 20-40 mph and hitting a rough patch of road, pothole, expansion joint, or uneven pavement, the vehicle sometimes heavily sways left to right. It takes one to two seconds to stabilize after the swaying. My wife and I both experience it at different times - we say it "feels like a wheel is falling off" because it's so disorienting and concerning. It often happens unexpectedly with road surface that doesn't actually appear to be all that bad. The rear end feels particularly unstable, like the suspension can't control the vehicle's weight when it's swaying. It's not a small vibration - it's a pronounced side-to-side oscillation. Sometimes I need to make steering corrections just to keep the vehicle centered in the lane. This unpredictable swaying makes us nervous about driving in adverse weather conditions. We can't trust how the vehicle will react when hitting unavoidable bumps and road imperfections. We have noticed it over 50mph at times but it is much more rare at this speed -- though when it happens at this speed it is obviously much more concerning. At higher speeds the swaying does not seem as pronounced / dangerous as at lower speeds, thankfully. After researching online, I discovered many other EV9 owners reporting identical suspension problems. Multiple complaints describe the same lateral swaying, porpoising, and bump-steer behavior that we are experiencing. This appears to be particularly common among GT-Line models. The consistency of these reports suggests this is a systemic defect affecting multiple vehicles, not an isolated incident with our particular vehicle. We have 11k miles on the vehicle now and this has been consistently happening since 200-300 miles brand new. We've mentioned to a dealer but it is very difficult to reproduce as it seems to happen randomly, even over the same stretch of rough road.