At what temp would a car not start?

Can't recall the last time I had a vehicle not start because of cold, and it can and has been well below 0F here over winter. Of course, making sure the battery is good is a must. Lot of cars use thinner oil than the old days. They'll usually start a little "stiff" but can loosen up a little once the fluids warm up. I wouldn't recommend starting and driving immediately. Here's a snap from my d
dash as I started off to work in the morning of 2019.

It depends on the car, the battery age and how good your gasoline is.

My car has started with no special treatment at -25F

3° below 0