Which parts fail
Components named in complaints (accelerator pedal, throttle, sudden acceleration, cruise control).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2016 Kia Optima owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owned a 2016 KIA OPTIMA. The contact stated that while driving at 30 MPH occupied with her husband the contact heard a noise coming from the rear of the vehicle and smoke coming from the rear of the vehicle as you looked in the drive side rear view mirror and while depressing the brake pedal attempting to come to a complete at the traffic light, the brakes failed to work a intended. No warning light illuminated. The contact mention she kept trying to depress the brake pedal, however the vehicle kept accelerating causing the vehicle to crash into a ditch, go around a telephone poll, crashing into a rock garden which allowing the vehicle to come to a complete stop. The vehicle was towed to a towing lot call interstate towing then the vehicle was then towed by insurance company to a collision center. No injuries were sustained. No medical attention. …
On [redacted] I was proceeding to come up to the stop sign when out of no where the car started rapidly accelerating and when I proceeded to step on the brakes it wouldn't stop it only sped up more. And caused a server accident that left me with serious injuries. And I cause of the defect they found me at fault said I failed to yield at a stop sign. The car never was fixed from the 2 times the motor has to be replaced by Galena Kia in fort Myers fl. They even caused the ac to go power retarded and wouldn't work half the time.
It started shaking really bad out of no where , then wasn't going faster than 80 then down to 65 but wouldn't go more than 80 with my foot all the way on the gas. As soon as I made it to work tonight the car cut off. I got a jump the car was still shaking & wouldn't stay on if I let my foot off of the gas. I started it again without the cables but it cut right back off. I saw on cars.com it's a recall for the similar thing, number Sc172. I have been having fuel leaks for a while and had my knock sensor replaced from a previous recall. Now I have no way home.
1) Rear passenger window failed a couple months ago. I believe it was regulator, not 100% sure. Cost me a couple hundred to fix. Now, few months later, the driver side rear window has failed. I rarely use the windows so I believe the failing parts are Kia known manufacturing defect. The dealer acknowledged that it's a known problem with the vehicles like mine and even suggested the other one is going to fail soon. Now it has. If the dealership is aware then it's likely a Kia flaw. If it's a know manufacturing flaw, shouldn't Kia should be fixing them instead of making customers spend upwards of $1k+ to fix both windows? 2) cruise control cuts off or doesn't set and menus won't go back to speedometer. While trying to set cruise control, it gets into the menu and won't go back to the speedometer. Sometimes I have to pull over and stop to get the cruise control to work again. …
Driving along the interstate approximately 70 mph, the vehicle jerked with knock sound then lost acceleration speed. At the same time, the check engine light started blinking. I pulled over to the side of the interstate put the car in park. I put it back in drive and slowly attempted to accelerate again. I was able to make it home because I was only about a mile and a half away, but I the acceleration was very slow and there wasn't much power behind it. At a speed of about 45-50, the vehicle barely seemed to have much power.
When accelerating the car will randomly loose all power from the engine. The electrical systems will stay on but the car RPMs will drop to zero. The accelerator will not provide acceleration when being pressed. The car has to be turned off and then turned back on for power to be restored. The check engine light, the oil light and another warning light will come on.
While driving the car will not accelerate past 49mph in turbo mode and 61mph in regular mode and rpm will not go above 1800. And it jerks and studders. Blinking check engine light and consumes a ridiculous amount of oil even though regular maintenance performed. I have read several engine issues with this model and cannot find recall info
Driving 80 miles an hour several hours from home on a major interstate and my car shut off. Pulled over on side of interstate and check engine light came on and car won't accelerate and is making a knocking noise
On 2/24 I was driving on Ben Hill Griffin Parkway, I was in the middle lane going thru an intersection, when suddenly while attempting to accelerate to go thru the light, all of my dash lights came on and the gas petal stopped working completely. I had cars in front, behind and on sides of me and I was unable to move out of the way. I attempted to restart the car to no avail. This could have been an incredibly deadly and dangerous situation and was extremely scary. With help I was able to move my car out of the way, call a tow truck and have it taken to the nearest Kia Dealership (Galeana Kia, 14483 Tamiami Trail, Ft. Myers) who advised they would evaluate the car and get back to me the next day. Tuesday I got word that my engine had seized and there was less than 1 qt of oil in it. I couldn't believe this as I just had an oil change 6 weeks prior. …
While we were driving home (3 people in my car), with no notice, my car lost complete acceleration and broke down while we were on the highway. We hardly had notice to understand what was happening, let alone the other cars/people behind us on the highway where we almost got hit before being able to pull over to the side of the highway. We then had to wait for a tow-truck, again, on the shoulder of a very busy highway. Later, I came to find out that this was "sudden and unexpected engine failure" that occurs in multiple models of Kia and Hyundai that was included in the Hyundai and Kia Engine Litigation, Case No. 8:17-cv-00838, and Hyundai and Kia Engine Litigation II, No. 8:18-cv-02223-JLS-JDE, New Theta II Class Action Lawsuit. …
NHTSA investigations
Throttle control system vulnerabilities
The Office of Defects Investigation (ODI) of the National Highway Traffic Safety Administration (NHTSA) received a petition letter dated October 10, 2021, requesting an investigation of possible defects in the electronic throttle control (ETC) system on certain Kia vehicles resulting in the opening of DP21-003.
Acceleration complaints in other Optima years
Frequently asked questions
How common are acceleration problems on the 2016 Kia Optima?
NHTSA has 29 complaints about the speed control & acceleration of the 2016 Kia Optima, 4% of the model year's 759 complaints. The component named most often is cruise control (1 mentions).
Is there a recall for 2016 Kia Optima acceleration problems?
No. NHTSA lists no speed control & acceleration recall for the 2016 Kia Optima, though it has 5 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2016 Kia Optima acceleration problems start?
Half of the complaints with a recorded mileage happened before about 39,000 miles, and 28% before 25,000 miles.
Is it dangerous?
Owners linked 2 crashes, 1 fire and 2 injuries to speed control & acceleration problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.