My 04 Optima EX 4cyl just started rattling on the passenger front door a few weeks ago. It started as only rattling when the passenger seat was empty, but now I'm noticing it even when there is a person in the seat. The noise stops when the car is idle, and only seems to rattle on bumpy roads. I don't know if that helps, but I'm planning on asking them to check it out at my next oil change in a month or so.
Other than that I love how quiet my Optima is, especially when I compare to other vehicles' highway noise
