Hey all new 04 a4 1.8 quattro owner here car has 74,000 miles on and noticed recently a high pitched whining noise from the mid or rear of the car maybe even a spinning kind. The noise happens when I start and at idle but goes away after a certain speed usually 40 to 50 but sometimes goes away completely after driving for a while. Seems to be worse as it gets colder. No check engine lights or any proformance issues because of it. Bought it from a lady in her 60s not one sign of missuse and has over 25 records of service so I don't seem how anything could be worn yet. Any ideas? I had my mechanic test drive it with me and he didn't think anything of it thought it was rusty brakes possible but I just got 4 new brakes and rotors same noise. Thanks!

-Also it goes away when i hit the gas and comes back when i let off or idle

 

well if you hear it at idle, it cant be the brakes!

replace the fuel filter, the sound you hear is the fuel pump straining. if it doesnt go away with a new filter, you will probably need a new pump.

 

If it's the fuel pump whining, you should also be able to hear that noise with the key in the on position, but before you actually crank the engine. Can you hear it then? And does it sound like it's coming from the back seat?

At 74k miles, you're due for a fuel filter anyway, so it's definitely worth replacing even if it doesn't solve the whining.