Yeah here in South Africa masks are mandatory if you go outside or in shops, Malls etc.
Not needed in vehicles if by yourself our with close family.
This was implemented months ago and fines can be imposed for not wearing one but lots of people go around with their noses exposed or the mask hanging down!
I personally wear my mask while driving....a bit paranoid that the virus could get sucked into the cabin via the air vents....I have some co-morbidities that compromise my system!
Years ago a Greek member on Lost posted pictures of a neat plastic cover with filter that fitted over the existing grid letting air into the cabin...would be possible to make one up I suppose.
I think what needs to be done as well is not let the air build up inside the cabin so the air needs a clean exit point. Behind the Glovebox is a mesh that gets gunged up by dirt etc. and needs a good brush and vacuum every now and then!