Sorry for late reply, after check with our designer, we have 3 reasons to set FCWS limit as 40km/h.
1. Avoid parking noise, we think parking speed almost during 10-25 km/h, to avoid the edge of range, the trigger limit must higher than 30km/h.
2. Consider of the dangerous speed, we think fatal accident speed most over 40 km/h.
3. Some of other brand in market, set this limit as 35km/h.
So after discussing, we decide set this limit as 40km/h, please feel free to let us know if you still have any question.