Starting issues in extreme cold?

This may be a dumb question, but the dealership and testing hasn't helped. In a recent cold snap, where we had highs of 10 degrees (f) in Colorado, overnight was around 0. Several mornings, the car would fail to turn over on the first few tries, or sometimes not turning over at all. Normally I would associate this with a dying battery, but all battery discharge testing was OK when I went to dealership.

Most threads I was able to find in my searches sounded like fueling issues, etc, and were not problems with the engine turning over. This is the original battery on a '13, so it should have less than a year on it so far. Has anyone seen issues with the factory battery discharging in very cold weather? That kind of cold in Denver isn't frequent, but I'm a skier, so I'm concerned about getting stranded in the mtns one of these days..

My instinct is still to replace the battery, despite the tests, but I'd really prefer not to drop the coin if I don't have to, on a part that should be warrantied.

do you leave your radio and HVAC on when you turn off your car the night prior?

do you have KESSY?

Sounds like something is draining the battery... too new to be a battery problem. Did VW check the starter?

I haven't had that issue and mine has started at temps as low as -35C.

There is an amp installed but it's switched from aftermarket stereo remote line so there's zero draw measured from that. No abnormal drain was measured in an overnight test @ the dealership.

HVAC switches may be left in an ON position overnight - is there a known draw issue here? Or is it a question of excessive draw on the battery when those items are on when the car is started? I know that the starting attempts that failed were likely in combinations of switches on and off.

No KESSY here.

And regarding VW starter testing... there was no other physical testing beyond the battery drain, recharge, etc. Normal stuff. I believe any starter test would involve removal for bench test, right? Nothing like that was done. The plan for now is to wait for next cold snap and if it occurs again I'll do some logging myself via VAGCOM and document it with video, then go back and push for more review of the starter, etc.

My battery tested as good a day before it died (had to jump it 4 times that day). I don't trust those battery testers

Your battery should last more than a year, but if the tester says it's good, VW will never replace it unfortunately.

If I was you, i'd buy a battery and if it fixes it, try to get VW to cover the cost.

I bought mine in march 2012, park outside in MN winters and it still turns right over the first time everytime in -30F on the original battery. I know better than to try to get another winter out of it though.