Same complaint as was reported for a 2013 Sonata Hybrid with the cruise dropping below set speed when reengaging and at other times surging 5 or 10 miles above set speed. Been so scary a couple of times that I was not sure it was going to stop accelerating and had to shut it off. Seems to be almost normal in cold weather, however, in sunny California last year and sometimes here in Washington in the summer it was very noticeable. Generally this happens after about 20 on the freeway once things are warmed up.

Dealer cannot find any codes or find any problem when road testing. Truth be known, the cruise is basically useless in freeway traffic when this happens, and once it starts it is unreliable until the car is stopped long enough to cool down and then you get to start all over. Not bad when you are the only car on the road, but when traffic settles into a flow and you press resume and have to accelerate 5 or 6 MPH before it will finally begin to settle back (and sometimes goes below set before it finds its way home) to set speed, you overrun other vehicles.