My 1988 740 estate has vents in the driver and passengers footwell. Each winter I tape the vents closed as they cause a draught. How do the vents work as they seem to open and close at will. The driver vent is now broken ( plastic) so I have taken it off, looking to maybe buy another from a breaker. With it being summer the additional ventilation is welcomed but with the winter arriving shortly I am wondering if just to block up the vent and not bother to replace the vent as a breaker will probably want big bucks just for plastic. Thoughts on what to do.