no you dont. heated mirrors are standard on the gti, not sure but maybe standard on all mk5's. I know this as my car has NO options but still has heated mirrors!! 
Really? If they are standard, then why are they still sold to this day as an optional extra as part of the Winter Pack? *confused*
Probably for the same reason heated seats are listed as part of the winter pack when they come as standard (on the Ed30 anyway, not sure about the GTI).
Winter pack = heated seats, heated mirrors, headlight washers and heated washer jets. My car came with the first three as standard making the winter pack option an expensive price to pay seeing as all I got extra was the heated washer jets! A bit naughty on VW's part really but I didn't realise until I'd already specced the winter pack on my car
