I am someone who tends to turn dashboard lighting down to have best visibility outside the car when driving at night.
I find the 3 to be fine at night, with the screen set to "auto". It typically sets to 5% for me (not sure why different to Paulo).
The screen has a good contrast level with quite deep blacks - it doesn't have significant backlight bleed add the dark colours of night mode are effective.
Something quite significant about the model 3 at night is that there are no other light sources - no illuminated instrument cluster directly in front of you and no other significant cabin illuminations (e.g. Panels of illuminated buttons, footwell lighting, "ambient" lighting (can not understand this myself, but as I said, im someone that likes the cabin dark dark when driving at night)), which is good. The screen is basically the only light source in the car at night.