Buzzing Noise
 

I just bought my first Benz and am totally new to them in every way. I noticed while the car was running yesterday that an airy whistle was coming from the rear end of the car.

I thought I might of ran over something and that air was leaking from the tire. When I posted my head nearer to the rim I decided it was more of an electrical buzzing/whistle instead.

Any idea on what this might be? Is it a problem or is it just native to the car? It's a '94 E320.

its called your fuel pump (located above the rear axle) get used to it, and learn to love it, that sound is practically a Mercedes-Benz trademark.