From what I remember, when we had -10°F to -30°F temps (in Minnesota), it was only during small roads with lots of red lights/low speeds(during rush hour commuting to work), the car would have trouble de-fogging the 2 rear windows. The windshield would be partially fogged but it wasn't totally covered but beginning to be. This only happened to me during extremely cold weather during slow commutes(major traffic, average speed within 2 miles was 5-10mph stop and go).
I know it's not a Mirage climate control but the image below is what I have it on 99% of the time.
I had my air blasted to maybe the 5th-6th bar during -10°F to -30°F temps.
Also, during frigid temps, I 'warm-up' the car for roughly 4-5 minutes with the heat to the max (89°F) on gauge, with the vent blowing at its max. From what I noticed, when it's between -10°F to -30°F, condensation builds up faster if you're in the car warming it up, doing lots of stop and go from traffic. Foggy windshield tends to go away if you're constantly driving as the engine is constantly moving the heat throughout. That's just my experience with dealing with frigid cold and a foggy windshield. I hope this helps.
View my fuel log 2015 Mirage DE 1.2 manual: 43.7 mpg (US) ... 18.6 km/L ... 5.4 L/100 km ... 52.5 mpg (Imp)