Just about to say the exact same thing Alex, great minds and all that
Mirror down on early cars was only available with the PDC, it was never an option with folding that I'm aware of but I could be wrong.
On later cars i.e the mk6 the mirror dip seams to be the norm,
I'm the exception has I think I am the only one to retro fit it anywhere other than giving the info to Scott(Golfman) has he now has it.
It involves a new mk6 door controller with the mirror dip and some basic wire swapping and stuff,
Darren