Two problems related to cruise control have been reported for the 2012 Hyundai Sonata Hybrid. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2012 Hyundai Sonata Hybrid based on all problems reported for the 2012 Sonata Hybrid.
While on cruise control at 68mph I was going down a small hill & my car suddenly accelerated from 68mph to 82mph at which point I disengaged my cruise control & the car decelerated . I noted the mileage & took the car to Hyundai. They found no abnormal event in the computer log. This begs the issue that I did have this event occur. I had the compute microcode upgraded to the last rev earlier this year.
Electrical smell like melting plastic wiring: first incident as noted above; 2nd incident on 1/29/2013, mileage 9227-on vehicle start up (engine warm as it was after earlier driving) same hot, melting wire type smell coming through climate control dash vents; 3rd incident on 4/12/2013-mileage 12,353-hot burning smell through heater vents occurring on/after climbing steep hill for a mile or so; 4th incident-4/16/2013, mileage 12538, location of incident same as 3rd incident, same hill climb, same smell occurring during drive. Reported to dealer. Could not be duplicated during service appt. No further incidents of burning smell to current date: 01/13/2014. Cruise control and transmission gear selection issues: first incident: around 1/20/2013; subsequent incidents periodically since then to current date of 01/14/2013: when on cruise control, speeds set at anywhere (40-60 mpg for these incidents), on coasting down or flat terrain transmission will shift from 6th (high) gear down to 3rd or 4th and hold that gear with engine rev ving accordingly, until I either manu-shift it back up to 6th, or, perhaps after 10 or more seconds it might shift into higher gear on its own. I have deliberately not disengaged cruise control during these incidents to continue to assess the condition. Related to this is occasional excessive acceleration as car can drop (on cruise) to below set speed as in a dip in the road, and then applying speed to get back to set speed, but, it will accelerate aggressively to as much as 10 mph above set speed before cruise control mode 'back' off the acceleration action, making the car feel like it is 'taking off'. This can happen often on certain roads at same transition points from coasting downward into a dip in the road, then (cruise control) reapplying power to get the car backup to speed. Rest will be sent in a second submission following this.