Observation/Symptoms:

1) k03, 100k miles, sound seems to come from the passenger side
2) As I accelerate slowly through 1, 2 and 3 gear I hear a very quiet but high pitch rapid fluctuation sound. Something like we_we_we_we_we_we.
3) The sounds does not stop when I let the car row in neutral.
4) The sound does not increase if I step on the pedal.
5) I can not hear the sound above 3 gear.
6) The wheel is firm above 60mph... sound from the wheel bearing?

Very interesting! What do you fellas think?

This just start happening after I hit a deer with the right side of my car. The damage was external/body ONLY.

 

if it doesnt increase as you accelerate then it probably isnt the turbo. It could possibly be the wheel bearing. See if the sound increases if you take a turn left at a speed above 35mph. If it does then it most likely is the wheel bearing. Let me knoe what you come up with.

 

Doesn't sound like a turbo to me. Did it sounds like maybe something was small and over looked during deer damage repair and is scraping or rubbing and then tire noise covers it up after 3rd. I would say a bearing, did it hit the tire area at all, look in there. Did you have the inner wheel lining out at all, look behind there.

 

@ drev500: The sound does not increase if I take a left turn at a speed above 35mph. I hope it's the wheel bearing, but it does not seems so.

@ audi ops: The damage was on the front right passenger side. The tire area was not involved.

This is a very strange occurrence. The sound disappears after the car warms up.

I will check the wheel bearing this weekend. I will also see if anything (fan, pulley, etc) is scrapping or rubbing anywhere.

In the worst case scenario the sound will increase after time and I might be able to diagnose the problem more precisely... 1) rubbing, 2) wheel bearing, 3) turbo going bad

 

I highly doubt it could be the turbo unless the deer got sucked into it. I do believe from what your saying it is the wheel bearing since it does quiet down when it warms up.

 

Haha, the deer did not get sucked into the turbo . Not this time. Bambi would have had bigger chances of getting sucked...

This reminds me of a blog title I recently read... "How do you stuff a 150 pound deer into the engine compartment of a BMW convertible?"

Wait, here are the pictures/answer (very sad, nasty and graphic):

http://www.flickr.com/photos/16266825@N02/1813301455/

 

Mo pics in your post but i know exactly what your talking about! That deer got effing OWNED

 

Have you checked the Heat shield behind the brake rotor to see if its rubbing the rotor?

 

The heat shield is okay. However, while I was under the car I noticed grease (360 degrees) around the boot. Take a look at this picture. Maybe this is related to the noise??

 

It's possible. Look around at all the axle components and make sure nothing is loose.