Under what circumstances are car plastic parts easy to crack?

The disadvantage of automotive plastic parts is that they have poor resistance to internal stress and are easy to crack.
Reasons for cracking of plastic parts:
1. It is easy to crack at low temperature.
2. It is easy to crack when exposed to chemicals.
3. Aging is easy to crack.
4. The product design is unreasonable and easy to crack.
In addition, there are some other reasons that can cause plastic parts to crack, such as excessive pressure during processing, long pressure holding time, molds, materials, etc., which can cause plastic parts to crack easily.