My Golf Gti mark 5 also makes a strange noise when its cold or left about for a while.
When you turn on the ignition it momentarily makes a strange squeeking vibration noise. When the engine is switched on the noise re-appears for while - depending on how cold or how long the car has been left. I recently started the car after being away for two weeks and it was bad.
Anyone else had this or know what it is?
I am guessing it is coming from the fuel pump?
Noise seems to be from behind but is hard to tell.
Thanks