Ok, this may sound a little crazy, but while I am washing my car, I frequently hear a humming sound eminating from the front right wheel well. It usually lasts for about 2-3 seconds. What could this possibly be? Of course the car is off and usually has been off overnight.

 

Just your car being in standby mode... If you were to look inside you would notice an amber light on the gearshift area also... takes it a while to go completly to sleep...

 

True, same situation happend to my sis's 325

 

I always suspected the PDC doing that front right thing when washing. It is usually shortly after parking and while the car is still asleep. It happens as I walk past the right front bumper - but only on occasions. Since you don't seem to have PDC listed, it must be some other "organ" going to sleep.

 

I have hurt that funny sound too. I thought it was the 'auto light robot'

 

It's definitely normal. I think it might have to do with circulation of fluid through the engine block - Last winter I really noticed that the engine stayed warm for a long time and because of this, the interior heated up very quickly even when the car had sat for several hours.

 

what about a sound coming from the rear somwhere where to the left arm of the trunk. can't tell the exact source.

I heard it the other day after i parked my car, i went on and on. I didn't wait for it to stop.