NHTSA Complaint #11689044 — 2025 HYUNDAI KONA

The cruise control operation is unusual and the speed can vary greatly while it's engaged in moderately hilly terrain (not extreme) on the interstate ([XXX] through Kentucky and Tennessee). With the cruise set at interstate speeds and starting to climb a hill, the speed can drop by as much as 6mph below set point as the cruise control very, very slowly starts to increase throttle to compensate for the grade. Eventually it will stop the deceleration at that up to 6mph speed below the set point, before slowly starting to accelerate back up to the set point. One instance I timed was 22 seconds between the speed first falling below the set point, down to 6mph below, before recovering back to the set point. Sometimes it overshoots the set point by 2mph, meaning it could cause you to exceed the speed limit and/or your intended driving speed if the uphill is long enough for the speed to fully recover itself. It is not an issue with vehicle power available as I can easily maintain an exact speed through the same hills using the throttle manually without cruise control, it is only an issue with how the cruise control is programmed or executed. An 8mph variance with cruise control on the interstate in non-extreme terrain is a safety concern because it makes the vehicle unpredictable by other drivers who are trying to time their maneuvers around trucks and other vehicles and when my car suddenly slows significantly next to them they have to suddenly change or abort their maneuvers. It has not been reviewed or inspected by anyone else. It is a rental vehicle and not available for inspection by request from me, but may be from the owner. There were no warning lights or any other indication there was a problem recognized by the vehicle. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)