One problem related to engine exhaust system has been reported for the 2012 Kia Motor Optima. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2012 Kia Motor Optima based on all problems reported for the 2012 Optima.
Strong smell of exhaust inside passenger area of car. Smell by 4 of 5 passengers. Car was a rental, so I do not know the VIN ore even the model year. With < 10,000 total vehicle miles, it may have been a 2012. I did find this note online regarding a similar problem wtih Hyundai sonata, that may or not be related. ( fyi-my 2011 sonata smells like exhaust inside the cab of the car unless I keep the button pushed for "inside air circulation". I called the dealer and as it turns out, this is a common problem with this model. A hose has to be replaced on the exhaust system. Hyundai is aware of the problem because many people have complained about the same issue.