This time, the buzzing was not in my head

Reason number forty nine to have an unnecessary panic attack:

The other evening, I was going through my house, getting ready for bed, turning off lights, closing doors, making all my regular routine rounds.

I check the garage to make sure the light is off, but when I open the door, there is a strange sound.

It's sort of a buzzing sound, sort of a clicking sound, sort of a humming sound.

I wander around the garage for a while, trying to find the source of the sound: it's clearly coming from the car.

The car is switched off, but I wonder: did I perhaps leave the key in the ignition? leave a switch at a funny setting?

No.

The sound is coming from under the back of the car, so I get down on my tummy, shine my flashlight around, stick my arm in and try to touch various parts of the car to see if any of them are vibrating.

It's completely baffling.

So, I do the Only Sensible Thing: I go back in to the house, sit down at my computer, and search the Web.

Sure enough, there are dozens of forums filled with discussions of this behavior, and after clicking a few times, one of the messages sends me back out to the car, to look in the glove compartment, in the Owner's Manual, where, on page 9, I find:

Noise from under the vehicle.

NOTE: You may hear a noise from under the vehicle approximately 5 to 10 hours after the engine is turned off. However, this does not indicate a malfunction. This noise is caused by the operation of the fuel evaporation leakage checking system and is normal. The noise will stop after approximately 15 minutes.

And it did.