For the last several days I've been hearing a moderately high-pitched sound coming from the engine bay, seemingly from the passenger side, as I drive. The sound is associated with engine RPMs of about 2-3K and is heard almost entirely when the engine is under load. When sitting in neutral, I can rev the engine through that range with little or no presence of the noise. It sounds a little bit like a "whine". Car performance seems unchanged, and good--no complaints there. In fact, I have the impression that the sound is more noticeable, perhaps more present, when the engine is in the RPM range above, under moderate load. Under higher load, I don't notice it, though of course there's more engine noise/sound in general then. Anyone got any idea what's causing it? Since it's now lasted several days, I'm planning a trip to the dealer come Monday to have them try to figure it out and eliminate it. That said, I'd love to have a good idea of what it is before then.