A while ago, I bought myself a cable for charging my iPod while it plays through the Aux socket, I am currently running the lead that goes to the 12 volt socket by the cup holders from the storage under the arm rest (where I keep the iPod) and I hate seeing wires laid everywhere.
Whilst drinking copious amounts of coffee while pouring over the various topics on the forums, I keep reading about there being a 12 volt socket under the armrest..... I have searched the car from front to back, and top to bottom.
I have one where the ash tray/cup holders are, I have one on the rear of the arm rest for people sitting in the rear seats to use, and I have one in the luggage area..... but there is definitely nothing other than the 3.5mm Aux socket under the arm rest in the storage area
My e70 is a Sept 2007 3.0d model, could this socket have been a manufacturer optional extra when my car was built or something that became a standard fit to later models?