[McLane]

hi from the old world
well, our e89 35i will be delivered in may
but i heard about the prob in a german Z4 forum
the solutions suggested in the forum were a range from using credit cards to de icing spray
no one suggested pooring hot water, due to the risk of the glass bursting

the toyota of my wife is not "garaged", and right now it is pretty cold:
-11 celsius, that is 12 fahrenheit
so every morning the windows are frosted...
the solution: no: not letting the car idle for an hour or so (to much wear to the engine)
use a small electric fan and after 30 mins the interior is cosy and warm and the windows de-iced
so in the case of the Z4:
park your car under your carport in the evening
before you lock your car: put the electric fan into your car
you should be able to close the door fully even with the cable running from the inside to the outside
in the morning you just have to plug it in (problably you have to use an extension cable) half an hour before you wanna start
your car will be de-iced
the interior warm and the doors (including the "working windows") will be working perfectly...