My car is buzzing.

Why would a brand new (<3k Miles) Subaru Impreza, which has been parked for 5 hours since getting home from work, be making a buzzing/whirring sound from underneath?
I notice it when I'm putting the garbage out now and then. It's not constant. Just now it stopped before I could try to pinpoint it.

Maybe it's trying to Transform. If it starts shape shifting you should get out right away.

Google is your friend.

Sounds like the fuel pump is running, could be normal for the car. If it starts doing it constantly, could be a the fuel pump relay.

Have you figured it out?
Was there a bomb? Did you run over a toy?
Is it your fuel pump? A GPS tracker?

if it was "normal" for the car then he have noticed it from the day he started driving it. Anyway if it's intermittent (he says it's not constant) a stuck relay or the wiring going to the relay makes a lot of senses just from my own experience as an electronic tech. Granted I'm talking about air traffic control equipment, not cars. Definitely whatever is buzzing/whirring gets power directly from the battery versus after the ignition switch, since it's doing it well after the car has been turned off. Anything intermittent is a bitch because you have to catch the problem occurring "in the act" so to speak.

It's purring. Love. That's what makes a Subaru.

Do you have keyless locks and ignition? Do you carry your subaru fob with you when you take out the garbage?

The proximity of the fob to the car as you take the garbage out may cause the car to wake-up in anticipation of your loving caresses.

Or it's just glad to see you.

You car is buzzing and it won't go, in case you don't know......

Car: Is that a fob in your pocket or are you happy to see me?

Sorry, I lost track of the thread right after I created it.
Yeah, I hear it only occasionally, usually when I'm putting out the garbage around 10PM. No, I don't have my fob with me at the time.
So fuel pump self-test, eh? Well okay then. Strange, but as long as it's normal.

Might be evaporation fuel emissions equipment recovering fuel.

Did you happen to fart close to it?

The driver's seat cushion could probably be a useful source of methane.

Okay, from the Subaru forums:

Off to check the manual (Like, who reads that shit anyway??)

Men.

Pfah!
I suppose you read the instructions when you build a model kit!

RTFM!

In my defense I'm not alone. Even the Subaru forums had a dozen "I dunno"s and wild guesses before someone chimed in with the right answer.
Has there ever been a car that even does this before? None of mine ever did.

Maybe it's not buzzing.

Perhaps it's humming and it's doing that because it doesn't know the words.

That's cool. Is it one of yours?

I still have one of the what-if bombers you inspired me to get and not build back in 02.

Oh no, I didn't do that. It's been around the Facebook modeling pages for a while.
But I guarantee some brave soul has kitbashed a model like that.