OK, it can have trouble at night, especially in B/W with IR and at the edges of the field of view like you have. There is a custom dark model that you may want to try.
Some things to try to help:
Uncheck the begin with leading edge - the headlight shine triggers before it can tell it is a car.
Add more photos for it to analyze in the + real time images. Try 10.
Make a Zone A that is the whole image and tell it under object detection Zone A
Change it to simple algorithm at night.
If none of that works, then add under the to cancel block banana
1 - Look at the BI log and see what detection times look like, even if there's no detection.
2 - Think about adding either the dark or combined models. The dark model, actually called extra dark, is on the DS web site. The combined model is hereon IPCT.
I use the following settings for custom models in the AI tab of the camera
"objects:0,combined" for day profiles
"objects:0,combined,dark" for night profiles