Wimp. -22 right now and I felt fine outside. The only problem was starting the car. My Civic Hybrid doesn't normally use the 12v starter. The car is normally started from the 144v electric batteries. But if my hybrid is parked outside for longer than 2 hours at below -20, the 144v batteries are too cold and the engine needs to be started from the 12v starter instead. So instead of starting under 1 second with the 144v battery, it takes over 2 seconds to crack start from the 12v battery. That, and I'm not accustom to hearing the cranking sound from my normally quiet car.