While attempting to accelerate from a stop the vehicle got to 30 to 35 mph and would not go any faster despite pressing gas pedal and rpms went up to 7 and 8. after pushing gas pedal several times the car will finally increase in speed which is very concerning given I drive on an interstate. This has happened 3 times in past 4 months and same exact thing at 10 mph and RPM went to 4 and 5 and car would not increase speed. I stopped vehicle and accelerated and then it operated normally. Dealership has been in unable to duplicate it and has questioned me several times about driving with two feet which I do not do and laying purse on console against shifter which I also do not do. 3 of the 4 times it happened it was at the beginning of my drive within first mile or so. 1 time was near end after about 20 miles. Purchased car used with 18000 miles on it and did not drive on interstate from July 2013 until March 2014 on regular basis.

- Summerville, SC, USA

I took my car into the Hyundai dealer for a 30,000 service. They said the computer has an upgrade to the software. After the upgrade, the cruise control speeds up by 4 - 5 miles per hour when it is set. For instance, if you set it at 65 mph, it will speed up to 69 or 70 mph and then slow back down to 65. It does this when you initially set the speed or if you brake and then hit the "resume" button. In the case of "resume", if you initially set it at 65 mph and use the brake to slow down and then use the "resume" button, the car will speed up to 69 or 70 before going back down to 65. The cruise control will do this no matter what speed you initial set it at. I took the car back in and the service people thought it was strange. So they said they ran the upgrade to the software again, but it has the same issue. They then told me that the surge in speed was within an acceptable tolerance range. I have owned many cars with cruise control and none of them have ever done that and this car did not do it prior to the software upgrade. It is pretty dangerous if you are not paying attention.

- Albuquerque, NM, USA

When I applied break my RPM idle goes up. I don't know if that is safe I show in other car RPM goes down. I took to dealer got oil change. And I asked why this happens. He told me to chack eco system. I chack eco system it was on off postion. I ask him when I bought car I never show RPM go up when I hate break. There no engine sing comesup on dashboard either. This really safety concern for my family. RPM should not go up when U hate breaks. It's should bring RPM down. RPM should go up when U hate gas padel. I get this. But when I go to any speed. And tried to applied break it should drop RPM should not go up.

- Tinleypark, IL, USA

Unintended acceleration, had to slam on brakes and put car into neutral in order to prevent shooting into a intersection of oncoming traffic. The car immediately threw a number of codes, and a engine control system condition code, check engine code.... dealer tells me when unloaded off the tow-truck that the brake pedal went to the floor, after 6 days of having the car the dealership service manager is telling me no problem could be found due to not being able to reproduce the problem.

- Paris, KY, USA

I had just pulled into a small rural parking lot and parked facing a wood fence in the afternoon. I had my foot on the brake and put the car into park. The car suddenly lurched forward about ten feet, knocking over a wood fence post and incurring $3,000 damage to the car. I still had my foot on the brake, and slammed it instantly as the car lurched. Fortunately, no person was walking along the sidewalk, and I had my seat belt in place. I insisted the car be towed to the nearest Hyundai dealer rather than to a local repair shop, since I wanted to find the cause of this acceleration malfunction. The dealer said they found nothing wrong, other than the front end damage. I insisted that Hyundai national send out an engineer to check the car. I have also found a report on the internet from kmov.com news in St. Louis 2/28/13, that three local owners there experienced sudden unintended acceleration. The case detailed in the news report was exactly like my experience of sudden lurching acceleration from a parked position, but the Hyundai engineer reported nothing was wrong. However, our experience documents an unintended acceleration problem unrelated to driver error. I have told Hyundai that I will absolutely not continue to drive this car.

- New York, NY, USA

Starting on 10/16/2013 when attempting to accelerate, the vehicle did not respond. Rpms were at 3K and when I attempted to accelerate, there was no response even when pushing the gas pedal all the way to the floor. In another incident on 10/17, when attempting to accelerate, rpms spiked at 6.5K and the vehicle would not shift. On 10/18 I attempted and succeeded in replicating both behaviors. When experiencing the spiking rpms without shifting condition, I manually shifted the vehicle with the paddle shifter to get it to up shift. When the car began shifting again in on it's own, it then downshifted and an attempt to accelerate was met with no response even when pressing the accelerator all the way to the floor. These behaviors create dangerous driving conditions that prevent the driver from moving the car through an intersection or accelerating to get to speed to merge into traffic. I am taking the car in to have the dealer look at it today.

- Leesburg, VA, USA

On 09/22/13, I left for a 75 mile trip. When I first started my car that morning, I noticed it was moving sluggishly, but thought it was due to our overnight chilly temperatures. I drove the short distance to the interstate. As I attempted to merge onto the interstate, I had the most frightening experience of my life. I pressed on the accelerator to prepare to merge and discovered that I had practically no acceleration! my car got to between 5000 and 6000 rpms before it shifted out of first gear! at that point, I was going approximately 45 mph while trying to merge onto an interstate, in front of a semi that would not get over for me to merge. I literally had my accelerator pedal pushed to the floor, as the car again hit between 5000 and 6000 rpms to shift into second gear! I was able to eventually get my car to 65 and turn on the cruise control. I double checked to make sure I was in drive (rather than neutral or manual--no dashboard lights on). On occasion during that drive, I turned off the cruise and hit the accelerator to see if what I had experienced was a fluke'it was not. My accelerator was literally mashed to the floor as my car's speed slowly lurched higher, while my rpms raised above 5000 before shifting to the next gear. Once I returned home, I turned off my car for a few minutes, before restarting the vehicle to test it. The transmission problem was gone (although I question whether my turbo is still working effectively, as it seems less responsive). Today, I took my car to the local car dealership to address the recent Sonata recall, and I also requested they examine my transmission, describing the above incident to them. I noted that other drivers mentioned that a waste gate' issue appeared to be causing the shifting problems. They could find no problems and suggested I shifted into manual accidentally.

- Champaign, IL, USA

Car in park, key in ignition-motoridling--wife and I awaiting to board ferry car suddenly revved very high with tach over 5--checked car was in park no obstruction (mat etc..) or foot touching gas pedal--killed ignition to stop uncontrolled revving of engine. Four witnesses ti incident--two in car, two standing next to vehicle. Called dealer immed and made appointment to have car checked---first uncontrolled incident on cruise control April of 2013, second sudden increase August 5th 2013 again on cruise control--dealer found brake switch problem after 8-05-13 sudden surge but claims "can"T replicate additional surges.. cruise control used on way to ferry. Car taken to dealer 8-26-13 again they can't replicate. Occurs when in cruise control more than 20-30 min. Or more--perhaps wiring or modules heating up--dealer no help!!!!!!

- Medford, NY, USA

Westbound on I-78 near harrisburg, pa while traveling on cruise control vehicle motor increased without driver input from 65mph to over 72mph to the point of 80mph before several hard foot pressures on brake disengaged cruise control. Car did not respond to normal brake pedal tap to disengage. Called dealer who suggested we not use cruise control and on return had them service--dealer could not replicate and returned car. On 8-05-13 which was next highway trip on 440W in staten island, NY while on cruise control at 60mph (flow of traffic) car suddenly made high revving motor noise, lurched forward and increased speed to 0ver 70mph--brake again did mot disengage car but heavy (very heavy) pressing on disengage button slowed car. Car to be looked at after our return--scheduled check 8-13-13.

- Medford, NY, USA

Cruise control would not disengage by hitting cancel or turning it off. It would only disengage by depressing brake pedal. I have been having problems engaging cruise control for about a week. The brake interlock switch was already replaced once, if it had failed again the only option would have been to put the car in neutral and shut it off.

- Gansevoort, NY, USA

The cruise control fails to engage every time you press it. Sometimes it works, sometimes it doesn't. dealer replaced the switch saying it was bad. Problem persisted so I took it back in. They cannot replicate it since it is intermittent therefore I cannot get this fixed.

- Franklin , TN, USA

The vehicle's cruise control failed to engage or disengage when used. The dealership was initially unable to replicate the problem, then replaced a headlamp switch. After this, the radio began turning completely off while driving, and the cruise control continued to act erratically. The dealership said they could not replicate the problem but replaced the radio. Several more times, the dealership stated they were unable to replicate the problem with the cruise control and radio. After contacting the manufacturer, the dealership looked at the car again and found loose pins in the connector to the fuse box.

- Tucson, AZ, USA

The contact owns a 2012 Hyundai Sonata. The contact stated that while at a complete stop, the vehicle suddenly accelerated. The contact mentioned that in order to maintain control of the vehicle, he engaged the brakes and shifted into neutral. The vehicle was taken to the dealer. The technician was unable to diagnose the failure. The manufacturer was made aware of the failure and stated that they would contact him at a later date. The vehicle was not repaired. The failure and current mileage was 18,000. N updated 4/24/13 the consumer stated the failure could not be duplicated. The consumer traded the vehicle in. The manufacturer requested the vehicle be held for further inspection. The vehicle would, intermittently, not shift into second gear. The air condition malfunctioned. Updated 06/05/2013

- O'fallon , MO, USA

My 2012 Hyundai Sonata turbo has the following persistent issue. When the vehicle sits over night, in cool weather conditions of about 60 degrees and/or lower, upon first start in the morning it will not rev past 4000 RPM (while driving) and as a result it doesn't have the power to merge onto the highway in a manner that I would consider safely. I know of a technical service bulletin that Hyundai has released that's suppose to resolve this issue however, I also have knowledge of about 10 vehicles with this same issue, some the issue persisted even after the dealer claimed to have repaired it. What I consider the main safety issue to be is; there is no indication/alert within the vehicle's dashboard illustrating the issue affecting the acceleration/performance. My vehicle has normal power city streets or at about 30 mph or less. I discovered the issue when trying to merge onto a highway, due to lack of acceleration power (which my vehicle should/did have), I was nearly rear-ended by a 18 wheeler as I was trying to get up to highway speed. This is a huge safety issue. No check engine light has ever turned on. My vehicle has never been in an accident and has about 13,000 miles on it now. I would greatly appreciate your attention on this hazardous matter. [xxx] information redacted pursuant to the Freedom Of Information Act (FOIA), 5 U.S.C. 552(B)(6).

- Bronx, NY, USA

I was driving down a hill that was not very steep, in good weather, with cruise control on at 60 mph. As the car went down the hill, the speed increased to 80, at which point in time I used my brake to slow down. The same thing has happened on numerous occasions with me alone and with others in the car, including a staff member of the dealership, who told me that this was normal behavior for a Hyundai Sonata and for the cruise control on his own vehicle. If I cancel cruise control in the middle of a hill, speed decreases or holds steady --it does not accelerate.

- Ithaca, NY, USA

The contact owns 2012 Hyundai Sonata. The contact stated that while driving 2 mph, he applied slight pressure to the accelerator pedal and the vehicle surged forward. The vehicle crashed into the wall of a garage as a result. There were no injuries. The dealer and manufacturer were not notified. The vehicle was towed to a repair shop for inspection but the failure was unknown at the moment. The vehicle was being repaired. The failure mileage was 4,500. Updated 07/13/12

- Allison Park, PA, USA

The contact owns a 2012 Hyundai Sonata. The contact stated that when depressing the accelerator pedal, his foot would swell, causing him to pay less attention to the road. The vehicle was taken to the dealer where they advised him that they were unable to diagnose the failure. The manufacturer was contacted and they offered no assistance. The contact only experienced this problem while driving his vehicle. The failure mileage was approximately 30. The VIN was unavailable.

- Shenandoah, PA, USA

Three problems cropped up immediately or shortly after initial ownership. The car pulls to the right, and the steering wheel must be turned to the left of center to compensate when driving on a flat surface. Second, the sunroof area developed a loud creaking sound when the car is driven through a turn or over uneven road surface. Third, and most alarmingly, the cruise control intermittently fails to disengage when the cancel button is pressed. It also intermittently fails to engage when the set button is pressed. If the cruise control has failed to disengage, tapping the brake or pressing the main on/off button will cause it to disengage. However, the confusion that comes from the cancel button failure may lead to an accident. The dealer cannot replicate the problem during a short test drive and refuses to replace or test the electronic modules.

- Jeffersonton, VA, USA