Just bought Sonata SE with 2.4L engine. At ~1,300 rpm and 35 mph the car makes a noticeable low frequency 'growling' or 'rumbling' noise. Can't tell if it's exhaust or intake manifold (or something else). Only occurs at that exact rpm/roadspeed point, especially if going up a slight incline. Goes away as soon as revs go above 1,500.

Dealer says car checks out OK, but I don't think that is a happy sound.

Any ideas?

 

I got the same noise too with my sonata and the service department told me all checks out. The only other problem that I am having is stereo problems, radio goes to "aux connected" when there is nothing connected to it and the usb does not play MP3's with the thumb drive as listed in the owners manual and they cant figure that one out either.