It impedes peripheral vision and imho should come under careless driving. They wouldn't get away with it in France :-

A French Muslim woman has been fined for wearing a full-face veil while driving a car.

Police in the western city of Nantes said the veil - which showed only her eyes - restricted her vision and could have caused an accident.



http://news.bbc.co.uk/1/hi/world/europe/8641070.stm