Yes, I said you will probably be the cause of any issues with reliability...not the gun. In extreme cold you will loose dexterity in your fingers quickly, could be as fast as the walk from the front door of where you work out to the parking lot where your car is, if not wearing gloves. Your eyes might start to water if it's windy and if you wear contacts they can temporarily freeze (had this happen to me). If you're wearing gloves can you get to the trigger? Can you reload with gloves on?
In any case, if there is prolonged exposure to subzero temperatures funny things can happen to any of the materials that make up the modern day poly semi-auto or even something as classic as a 1911. Guns are designed to withstand extreme pressures and heat, not necessarily the cold. Plastics and metal can become more brittle. Lubricant can freeze and become almost like a glue or epoxy. If you take the gun inside from the cold you will have to deal with condensation (wipe the gun down and make sure it is dry before going back outside).
At any rate, for poly guns, the Glock is a great gun for cold weather; large trigger guard, no levers or safety that need to be engaged and there is documented history of Glocks being successfully used by LEO in cold weather.
As far a lubrication, try finding some dry film lubricants like sentry solutions. Slip2000, which is what I have used, is also rated for extreme cold. I also use Frog lube which makers say is rated to -40F. There are good products out there that will work so there is no need to run it dry like some have said, however, less is better in the cold.