I wouldn't risk it with a plasma, I live here in Ontario (currently in the Barrie area) and believe me it gets frigid! Some mornings here have been as low as -30C...takes my car a couple times to start. At the same time, the TV would be in the cottage away from the elements and would only be exposed to the cold. Maybe keep it away from the windows or where there are drafts.
Another thing to consider is a vehicles' sound and video systems, for instance the Toyota Prius has an LCD screen in its dash to display functions. This is a permanent display that functions in extreme heat and cold, I've never heard of these units suffering due to temperature. As for the overall technology, I'd say yes an LCD could survive the frigid temperatures, just let it warm up a bit before turning it on. In the Prius, I don't have one (yet...lol) but I'd guess that if it was started on a frigid -30C morning, the LCD would turn on but might be a bit slow until it warms up...which doesn't take long. LED shouldn't physically differ that much from an LCD. Still wouldn't risk plasma.
