Hi

I haven't had this problem with my XF, but I have had a car do this in the past - not only that, when it starts freezing you'll find yourself with thick frost ON THE INSIDE!!

I don't understand the science of why it happens (something to do with a fast temp change outside and not fast enough inside I've been told) but the following seemed to work:

Before parking the car at night, I put the windows down and turn off the heater for the last couple of minutes of the journey. This cools the inside of the car down a lot (although freezes you in the process) and makes any temperature change a lot smaller when you've locked the car, thus avoiding the same amount of condensation / fog forming on the windows.

Also, as per the other post in the forum just now on fogging, make sure you give the windows a good clean to avoid moisture clinging to the dirt.

Anyone else got any other suggestions or know the reason for this?? All you clever folks speak up now...