Mine does it. Most of you are saying you hear it at high RPMs...mine's just the opposite. It disappears at about 5k RPMS and is most audible around 2k. Some people at work have asked me if it's turboed.
I dunno what causes it, but my son loves it. He'll be getting the car next year when he gets his license and is more stoked than I ever thought he'd be considering it's a 7 (almost 8) y/o sedan.
