UPDATE:
I visited the dealership on Saturday to have my rear
wings installed and to have that knocking sound looked at.
After a drive with the tech, he got out and looked at the trunk from inside. His initial diagnosis was that the trunk latch was not aligned properly.
I left the car with him and came back after a couple of hours when he called saying the problem has been fixed. I took a drive with him and couldn't hear the sound anymore. I was delighted. I dropped him off and when I drove back home, I heard the sound once again.
Since then, I have heard the sound again, but less frequently. So something has changed for sure. I was wondering about the trunk latch. I always felt that the trunk door wouldn't close easily. I had to almost half-slam the trunk door to get it to latch.
Any of you folks think these 2 are certainly related? Anyone care to shed light if indeed the trunk door is harder to close, than other cars? (I am comparing it to my previous Optima 2011)