One problem related to brake drum wheel cylinder has been reported for the 2011 Hyundai Sonata. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2011 Hyundai Sonata based on all problems reported for the 2011 Sonata.
Coming out of side street, going about 5-10 mph. Depressed brake to stop/slowdown and car (2011 Hyundai Sonata purchased in February 2010) just kept on going into intesection and up the road. Kept pressing pedal all the way to floor and car still kept going until it glided to a stopped. Travelled about 100-150 feet with no brakes and had use horn a few times to warn other drivers. After this I moved again and brakes worked fine. Very scary. . . Went out into a very,very busy street. Fortunately I hit no one and no other cars hit me. Will call dealer to report it and ask for further advice. Perhaps ice, snow, sand, etc. Got into pads/cylinders and temporarily seized the brakes? don't have VIN with me will report it later.