 I bought my 2015 Kia Optima in October 2014 brand new from the Pomona dealership.  My car currently has about 47,500 miles on it, less than 2 yrs old, and has had knocking noise when accelerating, white smoke out of tailpipe, and check engine light came on right before it started violently shaking.   I then had to have it towed to a Kia dealership. I have kept up with routine oil changes/maintenance.   After googling this issue, I found that there were MULTIPLE complaints with newer KIAs regarding the same issues.  I am hoping, unlike MANY of the complaints & class action lawsuit I read online, that my engine will be covered under warranty.  This engine needs to be RECALLED (like the Hyundai Sonata engine)!  I also spoke with my neighbor who has a Kia Optima with the same issues (Hers is making a loud knocking noise). I also have received comments from numerous friends on Facebook who complain of the same issue as well.  The dealership says its Oil Sludge.   I took care of my car like I should have & am stuck now in a hardship both financially & physically.  Super stressful!!! Especially when I have previously owned/leased 5 other cars before this with absolutely NO mechanical problems…My previous car was a Toyota Camry with over 100k miles on it and ran perfectly when I sold it to buy a new Kia.  I maintained it the same way I have maintained my Kia and the other cars I’ve had (Lexus, Nissan, Honda).  This is the first time I’ve ever had a major issue with a car I’ve owned… And it was bought brand new (unlike some of my other previous cars)! In speaking with a few different mechanics and friends who know a lot about cars, this seems to be a KIA engine issue, and they know of no cars that get oil sludge being this new and even cars who have gone without oil changes for 15k+ miles.  DON'T BUY A KIA!!!!!!!!!!!