Can't remember exactly which model you've got. It's a Toyota isn't it? I thought most of those have a specially designed transmission - so not quite a CVT as implemented in many other automatics, and the engines don't use quite the same approach as most petrol engines. The Toyota I used to drive was absolutely hopeless in snow, and if it snowed in Surrey I had to take a run at the short "hill" in our road, and keep revving up in order to get to the top - not far - perhaps 100 yards, but didn't always make it. Coming down was a nightmare it would slither from one side to the other, usually bumping into the kerbs.
If yours is good in snow then things must have improved quite a bit. On the other hand a Hyundai i10 - which is still going - would just go straight down without losing control.

