When the vehicle is moving between the lower edge of the door and the doorway, the mud often falls. On the Renault brand, the gap between the door and the door is designed to be constructive (because the seals are on the inside): it is ventilated, which means that it reduces the possibility of corrosion.
You can protect the Renault Fluence thresholds with special rubber bands, in the name of "pure thresholds".
