I ahve had one nagging issue with my 2011 Sonata and one new issue---any thoughts?
1. Hesitation when I step on the gas---this is an inconsistent-consistent problem. Unpredictible and whenever I tak it to be serviced --they can not reproduce it---but it happens routinely and more so in hot weather
2, Failure to start-I press the starter button--ecerything lights up--will n.t start--this is new in last month but is becoming an every day issue--but again, it does start and then it wont--takes 5-10 tries

 

Mine also has some hesitation in the summer time. It normally goes away when I turn off the ECO setting. The ECO setting reduces power to the powertrain to increase fuel mileage. Combined with a warm engine and the AC running, it creates a bit of a drag or hesitation.

For the starting issue, there is a brake-interlock feature for the push button start. That module, if it is not operating correctly, will cause the car not to start properly. Have it checked by the dealer.

 

I had a starting problem. The dealer replaced the Brake Switch and all is fine,

 

I also had the starting problem. The dealer replaced a switch under warranty fairly quickly.