Bad Mileage

I'm new to this forum - signed up specifically for this post - and I'm getting terrible City mileage. Not even remotely close. If my conversion is correct, the City mileage for the 2012 Hatchback 1.8L should be 28mpg - or approximately 8.5L/100km. I'm getting a stunning 14L/100km (as per most recent fill-up). I've been really gentle on acceleration, simply because I wanted to make sure it wasn't my driving behaviour. I consider the car broken in, because I have put almost 25,000km on it since January of this year. The only thing impacting my mileage beyond driving would be the fact that ok in northern Ontario, so sometimes I have the car idling for twenty minutes before taking out. Even so, I can't see that eating into my mileage that bad. It's getting really frustrating and I'm thinking of going to my dealer with my most recent numbers.

I'm from Timmins, so probably a few degrees colder than Hamilton area

I've got the Continuously Variable Transmission, which is also the source of another problem for me (which also may be affecting the mileage).

Does idling my car for ten minutes before I drive it really burn that much fuel, though? With the CVT, good driving behaviour, and a broken-in engine, I feel that my 2012 Versa should be getting better mileage than HALF of what the company advertises.

So basically you guys are saying that this delay in my CVT is normal in cold weather, and that driving it while it is doing this is harmless - if not beneficial?

I idled only because I thought this CVT issue was caused by the cold (which I guess it is), so I won't idle it as much anymore.