 I bought my 2009 Sonata new and I have had it for a year and half and have had to take it to the dealer 7 times in addition to it regular maintenance.  The upholstery of the driver seat was coming off within the first 3 months of having the car (3 trips total for that because the dealer did not have the part and then installed it incorrectly).  Then, the side view mirror became loose without any reason (no dent or damage) resulting in 2-3 trips to the dealer. Lastly, a whistling noise was coming from the engine and clicking sound was noted from the shift gear box. The whistling sound ended up being the catalytic converter which had to be replaced.