My guess is that it is your fuel pump that you are hearing.
I believe its under the passenger side carpet.
Underneath the vehicle. Under the rear passenger side door.
There are a couple of reasons why a 2001 Audi would make humming noises from the back while it is being driven. The first thing to check is the tires. If the tires are fine, check the wheel bearings.
that is probably your electic fuel pump nothing to worry about
Call an audi dealer...
Wheel bearing is on its way out.
Where is the fuse box on an Audi Q7 Quarto? Pull into the driveway last night everything OK. But this morning everything turns on and no starter. Tried to jump it and the same no start. Richard
On my 86 Audi 5000 the fuel filter is located under the hood on the passenger side, up top and close to the inner fender. Yours may be the same.
Possible wheel bearing going bad.
the battery is located under the rear seat, passenger side of the car. I belive there is a brackett you unscrew then take off the cables.
Its most likely a wheel bearing, I had the same problem about a year ago.
Audi Geman Volkswagen subsidiary which produces cars under the Audi brand.